From d568a43f6dbba3ba006304d95fd09862bd482a2f Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 23 Jul 2026 12:34:46 +0100 Subject: [PATCH 1/3] afs: Fix afs_fs_fetch_data() to set call->async Fix afs_fs_fetch_data() to set call->async on an async operation as does afs_fs_fetch_data64(). Fixes: eddf51f2bb2c ("afs: Make {Y,}FS.FetchData an asynchronous operation") Link: https://sashiko.dev/#/patchset/20260702144919.172295-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260723113452.566619-2-dhowells@redhat.com cc: Marc Dionne cc: Jeffrey Altman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Signed-off-by: Christian Brauner (Amutable) --- fs/afs/fsclient.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c index a2ffd60889f8..626e1d37b915 100644 --- a/fs/afs/fsclient.c +++ b/fs/afs/fsclient.c @@ -477,6 +477,9 @@ void afs_fs_fetch_data(struct afs_operation *op) if (!call) return afs_op_nomem(op); + if (op->flags & AFS_OPERATION_ASYNC) + call->async = true; + /* marshall the parameters */ bp = call->request; bp[0] = htonl(FSFETCHDATA); From 222052c6be186f2074b3a4d741d5de200f654c43 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 23 Jul 2026 12:34:47 +0100 Subject: [PATCH 2/3] afs: Fix afs_fs_fetch_data() to subtract transferred from len Fix afs_fs_fetch_data() to subtract subreq->transferred from subreq->len rather than adding it. Fixes: f28fc2010d62 ("afs: Eliminate afs_read") Link: https://sashiko.dev/#/patchset/20260713081022.2186481-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260723113452.566619-3-dhowells@redhat.com cc: Marc Dionne cc: Jeffrey Altman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Signed-off-by: Christian Brauner (Amutable) --- fs/afs/fsclient.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c index 626e1d37b915..1a3f186a6a11 100644 --- a/fs/afs/fsclient.c +++ b/fs/afs/fsclient.c @@ -487,7 +487,7 @@ void afs_fs_fetch_data(struct afs_operation *op) bp[2] = htonl(vp->fid.vnode); bp[3] = htonl(vp->fid.unique); bp[4] = htonl(lower_32_bits(subreq->start + subreq->transferred)); - bp[5] = htonl(lower_32_bits(subreq->len + subreq->transferred)); + bp[5] = htonl(lower_32_bits(subreq->len - subreq->transferred)); call->fid = vp->fid; trace_afs_make_fs_call(call, &vp->fid); From 4af1ec68d54b3871155914d584fb10669c41a861 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 23 Jul 2026 12:34:48 +0100 Subject: [PATCH 3/3] afs: Fix UAF when sending a message In afs_make_call(), there's a race with async call reception and destruction. If a call is dispatched that doesn't have call->write_iter set (used to specify the data content for FS.StoreData), then the first rxrpc_kernel_send_data() will not set MSG_MORE in the msghdr. Once rxrpc_send_data() queues the last request packet, the response could come in at any time and cause the call to be completed and put. However, afs_make_call() will look at the call again to see it ->write_iter should be handled - something it's only allowed to do if it has its own ref on the call. Whilst this is the case for synchronous calls, it isn't true for async calls such as FS.FetchData. There's also a potential UAF in afs_make_call() in the event that an asynchronous call is being sent, but the call fails in some way (e.g. it gets aborted from the server). The problem there is that afs_make_call() tries to abort a call if the rxrpc send fails, but the asynchronous notification from rxrpc may have caused the afs_call to be torn down. generic/650 plays games with randomly taking CPUs offline, and can interject a significant delay such that the call is deallocated before afs_make_call() gets to check call->write_iter - and a UAF ensues (caught by KASAN). BUG: KASAN: slab-use-after-free in afs_make_call+0x1c90/0x2210 [kafs] Read of size 8 at addr ffff888035e050e8 by task fsstress/1409 Fix this by making afs_make_op_call() give the op->call its own ref rather than transferring the caller's ref to it and then dropping the ref when afs_make_call() returns. This also means that the afs_make_call() func never loses its ref on the call now. Fixes: eddf51f2bb2c ("afs: Make {Y,}FS.FetchData an asynchronous operation") Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept") Link: https://sashiko.dev/#/patchset/20260702144919.172295-1-dhowells%40redhat.com Reported-by: Marc Dionne Signed-off-by: David Howells Link: https://patch.msgid.link/20260723113452.566619-4-dhowells@redhat.com cc: Jeffrey Altman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Signed-off-by: Christian Brauner (Amutable) --- fs/afs/internal.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 601f01e5c15f..290873bac89b 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -1421,7 +1421,7 @@ static inline void afs_make_op_call(struct afs_operation *op, struct afs_call *c { struct afs_addr_list *alist = op->estate->addresses; - op->call = call; + op->call = afs_get_call(call, afs_call_trace_get); op->type = call->type; call->op = op; call->key = op->key; @@ -1429,6 +1429,7 @@ static inline void afs_make_op_call(struct afs_operation *op, struct afs_call *c call->peer = rxrpc_kernel_get_peer(alist->addrs[op->addr_index].peer); call->service_id = op->server->service_id; afs_make_call(call, gfp); + afs_put_call(call); } static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t size)