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netfilter: nf_queue: fix possible use-after-free

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commit c387307024 upstream.

Eric Dumazet says:
  The sock_hold() side seems suspect, because there is no guarantee
  that sk_refcnt is not already 0.

On failure, we cannot queue the packet and need to indicate an
error.  The packet will be dropped by the caller.

v2: split skb prefetch hunk into separate change

Fixes: 271b72c7fa ("udp: RCU handling for Unicast packets.")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Florian Westphal 2022-02-28 06:22:22 +01:00 committed by Greg Kroah-Hartman
parent 3b9ba964f7
commit 4d05239203
3 changed files with 19 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/netfilter/nf_queue.h
View File

@ -37,7 +37,7 @@ void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *q
void nf_unregister_queue_handler(struct net *net); void nf_unregister_queue_handler(struct net *net);
void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict); void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict);
void nf_queue_entry_get_refs(struct nf_queue_entry *entry); bool nf_queue_entry_get_refs(struct nf_queue_entry *entry);
void nf_queue_entry_free(struct nf_queue_entry *entry); void nf_queue_entry_free(struct nf_queue_entry *entry);
static inline void init_hashrandom(u32 *jhash_initval) static inline void init_hashrandom(u32 *jhash_initval)

13
net/netfilter/nf_queue.c
View File

@ -100,16 +100,17 @@ static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry)
} }
/* Bump dev refs so they don't vanish while packet is out */ /* Bump dev refs so they don't vanish while packet is out */
void nf_queue_entry_get_refs(struct nf_queue_entry *entry) bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
{ {
struct nf_hook_state *state = &entry->state; struct nf_hook_state *state = &entry->state;
if (state->sk && !refcount_inc_not_zero(&state->sk->sk_refcnt))
return false;
if (state->in) if (state->in)
dev_hold(state->in); dev_hold(state->in);
if (state->out) if (state->out)
dev_hold(state->out); dev_hold(state->out);
if (state->sk)
sock_hold(state->sk);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
if (entry->physin) if (entry->physin)
@ -117,6 +118,7 @@ void nf_queue_entry_get_refs(struct nf_queue_entry *entry)
if (entry->physout) if (entry->physout)
dev_hold(entry->physout); dev_hold(entry->physout);
#endif #endif
return true;
} }
EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
@ -205,7 +207,10 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
__nf_queue_entry_init_physdevs(entry); __nf_queue_entry_init_physdevs(entry);
nf_queue_entry_get_refs(entry); if (!nf_queue_entry_get_refs(entry)) {
kfree(entry);
return -ENOTCONN;
}
switch (entry->state.pf) { switch (entry->state.pf) {
case AF_INET: case AF_INET:

12
net/netfilter/nfnetlink_queue.c
View File

@ -712,9 +712,15 @@ static struct nf_queue_entry *
nf_queue_entry_dup(struct nf_queue_entry *e) nf_queue_entry_dup(struct nf_queue_entry *e)
{ {
struct nf_queue_entry *entry = kmemdup(e, e->size, GFP_ATOMIC); struct nf_queue_entry *entry = kmemdup(e, e->size, GFP_ATOMIC);
if (entry)
nf_queue_entry_get_refs(entry); if (!entry)
return entry; return NULL;
if (nf_queue_entry_get_refs(entry))
return entry;
kfree(entry);
return NULL;
} }
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)