From 94f3b133168d1c49895e7cc6afbcf1cc0b354602 Mon Sep 17 00:00:00 2001 From: Luxiao Xu Date: Mon, 11 May 2026 18:52:09 +0200 Subject: [PATCH 01/14] batman-adv: fix tp_meter counter underflow during shutdown batadv_tp_sender_shutdown() unconditionally decrements the "sending" atomic counter. If multiple paths (e.g. timeout, user cancel, and normal finish) call this function, the counter can underflow to -1. Since the sender logic treats any non-zero value as "still sending", a negative value causes the sender kthread to loop indefinitely. This leads to a use-after-free when the interface is removed while the zombie thread is still active. Fix this by using atomic_xchg() to ensure the counter only transitions from 1 to 0 once. Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei [sven: added missing change in batadv_tp_send] Signed-off-by: Sven Eckelmann --- net/batman-adv/tp_meter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index 066c76113fc4..a4397aa881dd 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -451,7 +451,7 @@ static void batadv_tp_sender_end(struct batadv_priv *bat_priv, static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars, enum batadv_tp_meter_reason reason) { - if (!atomic_dec_and_test(&tp_vars->sending)) + if (atomic_xchg(&tp_vars->sending, 0) != 1) return; tp_vars->reason = reason; @@ -885,7 +885,7 @@ static int batadv_tp_send(void *arg) "Meter: %s() cannot send packets (%d)\n", __func__, err); /* ensure nobody else tries to stop the thread now */ - if (atomic_dec_and_test(&tp_vars->sending)) + if (atomic_xchg(&tp_vars->sending, 0) == 1) tp_vars->reason = err; break; } From 77098e4bea37af51d3962efa88a5af2ea5e1ac57 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sun, 10 May 2026 11:31:03 +0200 Subject: [PATCH 02/14] batman-adv: tp_meter: fix tp_vars reference leak in receiver shutdown The receiver shutdown timer handler, batadv_tp_receiver_shutdown(), is responsible for releasing the tp_vars reference it holds. However, the existing logic for coordinating this release with batadv_tp_stop_all() was flawed. timer_shutdown_sync() guarantees the timer will not fire again after it returns, but it returns non-zero only when the timer was pending at the time of the call. If the timer had already expired (and batadv_tp_stop_all() would unsucessfully try to rearm itself), batadv_tp_stop_all() skips its batadv_tp_vars_put(), and batadv_tp_receiver_shutdown() fails to put its own reference as well. Fix this by introducing a new atomic variable receiving that is set to 1 when the receiver is initialized and cleared atomically with atomic_xchg() by whichever side claims it first. Only the side that observes the transition from 1 to 0 is responsible for releasing the tp_vars timer reference, eliminating the uncertainty. Cc: stable@kernel.org Fixes: 3d3cf6a7314a ("batman-adv: stop tp_meter sessions during mesh teardown") Signed-off-by: Sven Eckelmann --- net/batman-adv/tp_meter.c | 13 +++++++++++-- net/batman-adv/types.h | 3 +++ 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index a4397aa881dd..ca6c3f6374bc 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -8,6 +8,7 @@ #include "main.h" #include +#include #include #include #include @@ -1156,6 +1157,9 @@ static void batadv_tp_receiver_shutdown(struct timer_list *t) spin_unlock_bh(&tp_vars->unacked_lock); /* drop reference of timer */ + if (WARN_ON(atomic_xchg(&tp_vars->receiving, 0) != 1)) + return; + batadv_tp_vars_put(tp_vars); } @@ -1374,6 +1378,7 @@ batadv_tp_init_recv(struct batadv_priv *bat_priv, ether_addr_copy(tp_vars->other_end, icmp->orig); tp_vars->role = BATADV_TP_RECEIVER; + atomic_set(&tp_vars->receiving, 1); memcpy(tp_vars->session, icmp->session, sizeof(tp_vars->session)); tp_vars->last_recv = BATADV_TP_FIRST_SEQ; tp_vars->bat_priv = bat_priv; @@ -1546,8 +1551,12 @@ void batadv_tp_stop_all(struct batadv_priv *bat_priv) break; case BATADV_TP_RECEIVER: batadv_tp_list_detach(tp_var); - if (timer_shutdown_sync(&tp_var->timer)) - batadv_tp_vars_put(tp_var); + timer_shutdown_sync(&tp_var->timer); + + if (atomic_xchg(&tp_var->receiving, 0) != 1) + break; + + batadv_tp_vars_put(tp_var); break; } diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index daa06f421154..b9c0b7779122 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -1323,6 +1323,9 @@ struct batadv_tp_vars { /** @sending: sending binary semaphore: 1 if sending, 0 is not */ atomic_t sending; + /** @receiving: receiving binary semaphore: 1 if receiving, 0 is not */ + atomic_t receiving; + /** @reason: reason for a stopped session */ enum batadv_tp_meter_reason reason; From 1e9fab756f8395096d5bba7be0c373c4c8f5d165 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 2 May 2026 19:08:37 +0200 Subject: [PATCH 03/14] batman-adv: tt: reject oversized local TVLV buffers The commit 3a359bf5c61d ("batman-adv: reject oversized global TT response buffers") added a check to ensure that a global return buffer size can be stored in an u16. The same buffer handling also exists for the local data buffer but was not touched. A similar check should be also be in place for the local TVLV buffer. It doesn't have the similar attack surface because it is only generated from locally discovered MAC addresses but the dynamic nature could still cause temporarily to large buffers. Cc: stable@kernel.org Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific") Signed-off-by: Sven Eckelmann --- net/batman-adv/translation-table.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 05cddcf994f6..06548dae1039 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -877,12 +877,12 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, { struct batadv_tvlv_tt_vlan_data *tt_vlan; struct batadv_meshif_vlan *vlan; + size_t change_offset; u16 num_vlan = 0; u16 vlan_entries = 0; u16 total_entries = 0; u16 tvlv_len; u8 *tt_change_ptr; - int change_offset; spin_lock_bh(&bat_priv->meshif_vlan_list_lock); hlist_for_each_entry(vlan, &bat_priv->meshif_vlan_list, list) { @@ -900,8 +900,10 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, if (*tt_len < 0) *tt_len = batadv_tt_len(total_entries); - tvlv_len = *tt_len; - tvlv_len += change_offset; + if (check_add_overflow(*tt_len, change_offset, &tvlv_len)) { + tvlv_len = 0; + goto out; + } *tt_data = kmalloc(tvlv_len, GFP_ATOMIC); if (!*tt_data) { From b64963a2ceeb7529310b6cf253a1e540784422f4 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 2 May 2026 19:53:21 +0200 Subject: [PATCH 04/14] batman-adv: tt: fix negative tt_buff_len batadv_orig_node::tt_buff_len was declared as s16, but the field is never intended to hold a negative value. When a value greater than 32767 is assigned, it wraps to a negative signed integer. In batadv_send_other_tt_response(), tt_buff_len is temporarily widened to s32. The incorrectly negative s16 value propagates into the s32, causing batadv_tt_prepare_tvlv_global_data() to allocate a full sized buffer but populates only a small portion of it with the collected changeset. All remaining bits are kept uninitialized. Using an u16 avoids this type confusion and ensures that no (negative) sign extension is performed in batadv_send_other_tt_response(). Cc: stable@kernel.org Fixes: a73105b8d4c7 ("batman-adv: improved client announcement mechanism") Signed-off-by: Sven Eckelmann --- net/batman-adv/types.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index b9c0b7779122..888f337a194b 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -452,7 +452,7 @@ struct batadv_orig_node { * @tt_buff_len: length of the last tt changeset this node received * from the orig node */ - s16 tt_buff_len; + u16 tt_buff_len; /** @tt_buff_lock: lock that protects tt_buff and tt_buff_len */ spinlock_t tt_buff_lock; From fc92cdfcb295cefa4344d71a527d61b638b7bfc4 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 2 May 2026 19:53:21 +0200 Subject: [PATCH 05/14] batman-adv: tt: fix negative last_changeset_len batadv_piv_tt::last_changeset_len len was declared as s16, but the field is never intended to hold a negative value. When a value greater than 32767 is assigned, it wraps to a negative signed integer. In batadv_send_my_tt_response(), last_changeset_len is temporarily widened to s32. The incorrectly negative s16 value propagates into the s32, causing batadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but populates only a small portion of it with the collected changeset. All remaining bits are kept uninitialized. Using an u16 avoids this type confusion and ensures that no (negative) sign extension is performed in batadv_send_my_tt_response(). Cc: stable@kernel.org Fixes: a73105b8d4c7 ("batman-adv: improved client announcement mechanism") Signed-off-by: Sven Eckelmann --- net/batman-adv/types.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 888f337a194b..739439e2b235 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -993,7 +993,7 @@ struct batadv_priv_tt { * @last_changeset_len: length of last tt changeset this host has * generated */ - s16 last_changeset_len; + u16 last_changeset_len; /** * @last_changeset_lock: lock protecting last_changeset & From 94d27005016be15ffc638b2ecbc4d58805ad7b48 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 2 May 2026 19:47:11 +0200 Subject: [PATCH 06/14] batman-adv: tt: fix TOCTOU race for reported vlans The local TT based TVLV is generated by first checking the number of VLANs which have at least one TT entry. A new buffer with the correct size for the VLANs is then allocated. Only then, the list of VLANs s used to fill the VLAN entries in the buffer. During this time, the meshif_vlan_list_lock is held. But the actual number of TT entries of each VLAN can still increase during this time - just not the number of VLANs in the list. But the prefilter used in the buffer size calculation might still cause an increase of the number of VLANs which need to be stored. Simply because a VLAN might now suddenly have at least one entry when it had none in the pre-alloc check - and then needs to occupy space which was not allocated. It is better to overestimate the buffer size at the beginning and then fill the buffer only with the VLANs which are not empty. Cc: stable@kernel.org Fixes: 16116dac2339 ("batman-adv: prevent TT request storms by not sending inconsistent TT TLVLs") Signed-off-by: Sven Eckelmann --- net/batman-adv/translation-table.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 06548dae1039..f009cbf8a276 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -887,11 +887,8 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, spin_lock_bh(&bat_priv->meshif_vlan_list_lock); hlist_for_each_entry(vlan, &bat_priv->meshif_vlan_list, list) { vlan_entries = atomic_read(&vlan->tt.num_entries); - if (vlan_entries < 1) - continue; - - num_vlan++; total_entries += vlan_entries; + num_vlan++; } change_offset = struct_size(*tt_data, vlan_data, num_vlan); @@ -916,6 +913,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, (*tt_data)->num_vlan = htons(num_vlan); tt_vlan = (*tt_data)->vlan_data; + num_vlan = 0; hlist_for_each_entry(vlan, &bat_priv->meshif_vlan_list, list) { vlan_entries = atomic_read(&vlan->tt.num_entries); if (vlan_entries < 1) @@ -926,8 +924,15 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, tt_vlan->reserved = 0; tt_vlan++; + num_vlan++; } + /* recalculate in case number of VLANs reduced */ + change_offset = struct_size(*tt_data, vlan_data, num_vlan); + tvlv_len = *tt_len + change_offset; + + (*tt_data)->num_vlan = htons(num_vlan); + tt_change_ptr = (u8 *)*tt_data + change_offset; *tt_change = (struct batadv_tvlv_tt_change *)tt_change_ptr; From fa1bd704940b5bcbc32c0b28db9167405c8ee5e0 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 2 May 2026 20:47:34 +0200 Subject: [PATCH 07/14] batman-adv: tt: avoid empty VLAN responses The commit 16116dac2339 ("batman-adv: prevent TT request storms by not sending inconsistent TT TLVLs") added checks to the local (direct) TT response code. But the response can also be done indirectly by another node using the global TT state. To avoid such inconsistency states reported in the original fix, also avoid sending empty VLANs for replies from the global TT state. Cc: stable@kernel.org Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific") Signed-off-by: Sven Eckelmann --- net/batman-adv/translation-table.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index f009cbf8a276..2259b241e0b5 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -797,24 +797,26 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, s32 *tt_len) { u16 num_vlan = 0; - u16 num_entries = 0; u16 tvlv_len = 0; unsigned int change_offset; struct batadv_tvlv_tt_vlan_data *tt_vlan; struct batadv_orig_node_vlan *vlan; + u16 total_entries = 0; u8 *tt_change_ptr; + int vlan_entries; spin_lock_bh(&orig_node->vlan_list_lock); hlist_for_each_entry(vlan, &orig_node->vlan_list, list) { + vlan_entries = atomic_read(&vlan->tt.num_entries); + total_entries += vlan_entries; num_vlan++; - num_entries += atomic_read(&vlan->tt.num_entries); } change_offset = struct_size(*tt_data, vlan_data, num_vlan); /* if tt_len is negative, allocate the space needed by the full table */ if (*tt_len < 0) - *tt_len = batadv_tt_len(num_entries); + *tt_len = batadv_tt_len(total_entries); if (change_offset > U16_MAX || *tt_len > U16_MAX - change_offset) { *tt_len = 0; @@ -835,14 +837,26 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, (*tt_data)->num_vlan = htons(num_vlan); tt_vlan = (*tt_data)->vlan_data; + num_vlan = 0; hlist_for_each_entry(vlan, &orig_node->vlan_list, list) { + vlan_entries = atomic_read(&vlan->tt.num_entries); + if (vlan_entries < 1) + continue; + tt_vlan->vid = htons(vlan->vid); tt_vlan->crc = htonl(vlan->tt.crc); tt_vlan->reserved = 0; tt_vlan++; + num_vlan++; } + /* recalculate in case number of VLANs reduced */ + change_offset = struct_size(*tt_data, vlan_data, num_vlan); + tvlv_len = *tt_len + change_offset; + + (*tt_data)->num_vlan = htons(num_vlan); + tt_change_ptr = (u8 *)*tt_data + change_offset; *tt_change = (struct batadv_tvlv_tt_change *)tt_change_ptr; From 99d9958fa10fb684b2a8e2c48a8d704122721420 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Sat, 2 May 2026 21:25:19 +0200 Subject: [PATCH 08/14] batman-adv: tt: prevent TVLV entry number overflow The helpers to prepare the buffers for the local and global TT based replies are trying to sum up all TT entries which can be found for each VLAN. In theory, this sum can be too big for an u16 and therefore overflow. A too small buffer would then be allocated for the TVLV. The too small buffer will be handled gracefully by batadv_tt_tvlv_generate() and is not causing a buffer overflow - just a truncated reply. But this overflow shouldn't have happened in the first and the too small buffer should never have been allocated when an overflow was detected. Cc: stable@kernel.org Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific") Signed-off-by: Sven Eckelmann --- net/batman-adv/translation-table.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 2259b241e0b5..9f6e67771ffa 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -804,11 +804,18 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node, u16 total_entries = 0; u8 *tt_change_ptr; int vlan_entries; + u16 sum_entries; spin_lock_bh(&orig_node->vlan_list_lock); hlist_for_each_entry(vlan, &orig_node->vlan_list, list) { vlan_entries = atomic_read(&vlan->tt.num_entries); - total_entries += vlan_entries; + + if (check_add_overflow(vlan_entries, total_entries, &sum_entries)) { + *tt_len = 0; + goto out; + } + + total_entries = sum_entries; num_vlan++; } @@ -893,15 +900,22 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv, struct batadv_meshif_vlan *vlan; size_t change_offset; u16 num_vlan = 0; - u16 vlan_entries = 0; u16 total_entries = 0; u16 tvlv_len; u8 *tt_change_ptr; + int vlan_entries; + u16 sum_entries; spin_lock_bh(&bat_priv->meshif_vlan_list_lock); hlist_for_each_entry(vlan, &bat_priv->meshif_vlan_list, list) { vlan_entries = atomic_read(&vlan->tt.num_entries); - total_entries += vlan_entries; + + if (check_add_overflow(vlan_entries, total_entries, &sum_entries)) { + tvlv_len = 0; + goto out; + } + + total_entries = sum_entries; num_vlan++; } From 9cd3f16c320bfdadd4509358122368deb56a5741 Mon Sep 17 00:00:00 2001 From: Ruide Cao Date: Wed, 13 May 2026 11:58:15 +0800 Subject: [PATCH 09/14] batman-adv: fix fragment reassembly length accounting batman-adv keeps a running payload length for queued fragments and uses it to validate a fragment chain before reassembly. That accounting currently allows the accumulated fragment length to be truncated during updates. As a result, malformed fragment chains can bypass the intended validation and drive reassembly with inconsistent length state, leading to a local denial of service. Fix the accounting by storing the accumulated length in a length-typed field and rejecting update overflows before the existing validation logic runs. The fix was verified against the original reproducer and against valid fragment reassembly paths. Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Ruide Cao Tested-by: Ren Wei Signed-off-by: Ren Wei Signed-off-by: Sven Eckelmann --- net/batman-adv/fragmentation.c | 23 +++++++++++++++++------ net/batman-adv/types.h | 2 +- 2 files changed, 18 insertions(+), 7 deletions(-) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index f4e45cc25816..1152c2ce0c1e 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -80,9 +81,9 @@ void batadv_frag_purge_orig(struct batadv_orig_node *orig_node, * * Return: the maximum size of payload that can be fragmented. */ -static int batadv_frag_size_limit(void) +static size_t batadv_frag_size_limit(void) { - int limit = BATADV_FRAG_MAX_FRAG_SIZE; + size_t limit = BATADV_FRAG_MAX_FRAG_SIZE; limit -= sizeof(struct batadv_frag_packet); limit *= BATADV_FRAG_MAX_FRAGMENTS; @@ -143,7 +144,9 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, struct batadv_frag_packet *frag_packet; u8 bucket; u16 seqno, hdr_size = sizeof(struct batadv_frag_packet); + bool overflow = false; bool ret = false; + size_t data_len; /* Linearize packet to avoid linearizing 16 packets in a row when doing * the later merge. Non-linear merge should be added to remove this @@ -153,6 +156,7 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, goto err; frag_packet = (struct batadv_frag_packet *)skb->data; + data_len = skb->len - hdr_size; seqno = ntohs(frag_packet->seqno); bucket = seqno % BATADV_FRAG_BUFFER_COUNT; @@ -171,7 +175,7 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, spin_lock_bh(&chain->lock); if (batadv_frag_init_chain(chain, seqno)) { hlist_add_head(&frag_entry_new->list, &chain->fragment_list); - chain->size = skb->len - hdr_size; + chain->size = data_len; chain->timestamp = jiffies; chain->total_size = ntohs(frag_packet->total_size); ret = true; @@ -188,7 +192,11 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, if (frag_entry_curr->no < frag_entry_new->no) { hlist_add_before(&frag_entry_new->list, &frag_entry_curr->list); - chain->size += skb->len - hdr_size; + + if (check_add_overflow(chain->size, data_len, + &chain->size)) + overflow = true; + chain->timestamp = jiffies; ret = true; goto out; @@ -201,13 +209,16 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, /* Reached the end of the list, so insert after 'frag_entry_last'. */ if (likely(frag_entry_last)) { hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list); - chain->size += skb->len - hdr_size; + + if (check_add_overflow(chain->size, data_len, &chain->size)) + overflow = true; + chain->timestamp = jiffies; ret = true; } out: - if (chain->size > batadv_frag_size_limit() || + if (overflow || chain->size > batadv_frag_size_limit() || chain->total_size != ntohs(frag_packet->total_size) || chain->total_size > batadv_frag_size_limit()) { /* Clear chain if total size of either the list or the packet diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 739439e2b235..c8c3e8064f00 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -301,7 +301,7 @@ struct batadv_frag_table_entry { u16 seqno; /** @size: accumulated size of packets in list */ - u16 size; + size_t size; /** @total_size: expected size of the assembled packet */ u16 total_size; From a340a51ed801eab7bb454150c226323b865263cc Mon Sep 17 00:00:00 2001 From: Ruijie Li Date: Thu, 14 May 2026 16:13:25 +0800 Subject: [PATCH 10/14] batman-adv: clear current gateway during teardown batadv_gw_node_free() removes the gateway list entries during mesh teardown, but it does not clear the currently selected gateway. This leaves stale gateway state behind across cleanup and can break a later mesh recreation. Clear bat_priv->gw.curr_gw before walking the gateway list so the selected gateway reference is dropped as part of teardown. Fixes: 2265c1410864 ("batman-adv: gateway election code refactoring") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Ruijie Li Signed-off-by: Zhanpeng Li Signed-off-by: Ren Wei Signed-off-by: Sven Eckelmann --- net/batman-adv/gateway_client.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c index 51e9c081a2a4..a9d0346e8332 100644 --- a/net/batman-adv/gateway_client.c +++ b/net/batman-adv/gateway_client.c @@ -478,10 +478,14 @@ void batadv_gw_node_delete(struct batadv_priv *bat_priv, */ void batadv_gw_node_free(struct batadv_priv *bat_priv) { + struct batadv_gw_node *curr_gw; struct batadv_gw_node *gw_node; struct hlist_node *node_tmp; spin_lock_bh(&bat_priv->gw.list_lock); + curr_gw = rcu_replace_pointer(bat_priv->gw.curr_gw, NULL, true); + batadv_gw_node_put(curr_gw); + hlist_for_each_entry_safe(gw_node, node_tmp, &bat_priv->gw.gateway_list, list) { hlist_del_init_rcu(&gw_node->list); From 2d8826a2d3657cea66fb0370f9e521575a673871 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Wed, 13 May 2026 09:01:34 +0200 Subject: [PATCH 11/14] batman-adv: dat: handle forward allocation error batadv_dat_forward_data() calls pskb_copy_for_clone() to duplicate an skb for each DHT candidate, but does not check the return value before passing it to batadv_send_skb_prepare_unicast_4addr(). That function dereferences the skb unconditionally, so a failed allocation triggers a NULL pointer dereference. Skip forwarding to the current DHT candidate on allocation failure. Cc: stable@kernel.org Fixes: 785ea1144182 ("batman-adv: Distributed ARP Table - create DHT helper functions") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Reviewed-by: Yuan Tan Signed-off-by: Sven Eckelmann --- net/batman-adv/distributed-arp-table.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c index 3efc4cf50b46..0a8bd95e2f99 100644 --- a/net/batman-adv/distributed-arp-table.c +++ b/net/batman-adv/distributed-arp-table.c @@ -696,6 +696,9 @@ static bool batadv_dat_forward_data(struct batadv_priv *bat_priv, goto free_orig; tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC); + if (!tmp_skb) + goto free_neigh; + if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb, cand[i].orig_node, packet_subtype)) { From 6c65cf23d4c6170fcf5714c32aa64689718cb142 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Wed, 13 May 2026 09:01:35 +0200 Subject: [PATCH 12/14] batman-adv: tp_meter: avoid use of uninit sender vars batadv_tp_recv_ack() and batadv_tp_stop() are only valid for tp_vars in the BATADV_TP_SENDER role. When called with a BATADV_TP_RECEIVER role, it proceeds to read sender-only members that were never initialized, leading to undefined behavior. This can be triggered when a node that is currently acting as a receiver in an ongoing tp_meter session receives a malicious ACK packet. Guard against this by checking tp_vars->role immediately after the lookup and bailing out if it is not BATADV_TP_SENDER, before any of those members are accessed. Cc: stable@kernel.org Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Reviewed-by: Yuan Tan Signed-off-by: Sven Eckelmann --- net/batman-adv/tp_meter.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index ca6c3f6374bc..a3593d104caa 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -664,6 +664,9 @@ static void batadv_tp_recv_ack(struct batadv_priv *bat_priv, if (unlikely(!tp_vars)) return; + if (unlikely(tp_vars->role != BATADV_TP_SENDER)) + goto out; + if (unlikely(atomic_read(&tp_vars->sending) == 0)) goto out; @@ -1101,12 +1104,16 @@ void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst, if (!tp_vars) { batadv_dbg(BATADV_DBG_TP_METER, bat_priv, "Meter: trying to interrupt an already over connection\n"); - goto out; + goto out_put_orig_node; } + if (unlikely(tp_vars->role != BATADV_TP_SENDER)) + goto out_put_tp_vars; + batadv_tp_sender_shutdown(tp_vars, return_value); +out_put_tp_vars: batadv_tp_vars_put(tp_vars); -out: +out_put_orig_node: batadv_orig_node_put(orig_node); } From bc62216dc8e221e3781afa14430f45208bfa9af9 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Wed, 13 May 2026 09:01:36 +0200 Subject: [PATCH 13/14] batman-adv: frag: disallow unicast fragment in fragment batadv_frag_skb_buffer() is called by batadv_batman_skb_recv() when a BATADV_UNICAST_FRAG packet is received. Once all fragments are collected and the packet is reassembled, batadv_recv_frag_packet() calls batadv_batman_skb_recv() again to process the defragmented payload. A malicious sender can craft a BATADV_UNICAST_FRAG packet whose reassembled payload is itself a BATADV_UNICAST_FRAG packet (matryoshka-style nesting). Each nesting level recurses through batadv_batman_skb_recv() without bound, growing the kernel stack until it is exhausted. Since refragmentation or fragments in fragments are not actually allowed, discard all packets which are still BATADV_UNICAST_FRAG packets after the defragmentation process. Cc: stable@kernel.org Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Reviewed-by: Yuan Tan Signed-off-by: Sven Eckelmann --- net/batman-adv/fragmentation.c | 35 ++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index 1152c2ce0c1e..4a594aa2ebf6 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -304,6 +304,31 @@ batadv_frag_merge_packets(struct hlist_head *chain) return skb_out; } +/** + * batadv_skb_is_frag() - check if newly merged skb is gain a unicast packet + * @skb: newly merged skb + * + * Return: if newly skb is of type BATADV_UNICAST_FRAG + */ +static bool batadv_skb_is_frag(struct sk_buff *skb) +{ + struct batadv_ogm_packet *batadv_ogm_packet; + + /* packet should hold at least type and version */ + if (unlikely(!pskb_may_pull(skb, 2))) + return false; + + batadv_ogm_packet = (struct batadv_ogm_packet *)skb->data; + + if (batadv_ogm_packet->version != BATADV_COMPAT_VERSION) + return false; + + if (batadv_ogm_packet->packet_type != BATADV_UNICAST_FRAG) + return false; + + return true; +} + /** * batadv_frag_skb_buffer() - buffer fragment for later merge * @skb: skb to buffer @@ -337,6 +362,16 @@ bool batadv_frag_skb_buffer(struct sk_buff **skb, if (!skb_out) goto out_err; + /* fragment in fragment is not allowed. otherwise it is possible + * to exhaust the stack when receiving a matryoshka-style + * "fragments in a fragment packet" + */ + if (batadv_skb_is_frag(skb_out)) { + kfree_skb(skb_out); + skb_out = NULL; + goto out_err; + } + out: ret = true; out_err: From d5487249a81ea658717614009c8f46acc5b7101a Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Wed, 13 May 2026 10:43:54 +0200 Subject: [PATCH 14/14] batman-adv: tp_meter: directly shut down timer on cleanup batadv_tp_sender_cleanup() was calling timer_delete_sync() followed by timer_delete() to guard against the timer handler re-arming itself between the two calls. This double-deletion hack relied on the sending status being set to 0 to suppress re-arming. Replace both calls with a single timer_shutdown_sync(). This function both waits for any running timer callback to complete (like timer_delete_sync()) and permanently disarms the timer so it cannot be re-armed afterwards, making re-arming prevention unconditional and self-documenting. The re-arming property is also required because otherwise: 1. context 0 (batadv_tp_recv_ack()) checks in batadv_tp_reset_sender_timer() if sending is still 1 -> it is 2. context 1 changes in batadv_tp_sender_shutdown() sending to 0 and in this process forces the kthread to stop timer in batadv_tp_sender_cleanup() 3. context 0 continues in batadv_tp_reset_sender_timer() and rearms the timer -> but the reference for it is already gone Cc: stable@kernel.org Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation") Signed-off-by: Sven Eckelmann --- net/batman-adv/tp_meter.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index a3593d104caa..1fd1526059d8 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -401,13 +401,7 @@ static void batadv_tp_sender_cleanup(struct batadv_tp_vars *tp_vars) batadv_tp_list_detach(tp_vars); /* kill the timer and remove its reference */ - timer_delete_sync(&tp_vars->timer); - /* the worker might have rearmed itself therefore we kill it again. Note - * that if the worker should run again before invoking the following - * timer_delete(), it would not re-arm itself once again because the status - * is OFF now - */ - timer_delete(&tp_vars->timer); + timer_shutdown_sync(&tp_vars->timer); batadv_tp_vars_put(tp_vars); }