linux.git/fs/afs, branch v7.2

afs: Fix UAF when sending a message

2026-07-28T07:20:44+00:00

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)

afs: Fix afs_fs_fetch_data() to subtract transferred from len

2026-07-28T07:20:44+00:00

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)

afs: Fix afs_fs_fetch_data() to set call->async

2026-07-28T07:20:44+00:00

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)

afs: Fix afs_edit_dir_remove() to get, not find, block 0

2026-07-23T09:32:40+00:00

Fix afs_edit_dir_remove() to use afs_dir_get_block() to get block 0 rather
than afs_dir_find_block() as the latter caches the found block in the
afs_dir_iter and may[*] switch out the page it's on if another
afs_dir_find_block() is done.  This parallels what afs_edit_dir_add() does.

[*] There's more than one block per page.

Fixes: a5b5beebcf96 ("afs: Use the contained hashtable to search a directory")
Closes: https://sashiko.dev/#/patchset/20260706153408.1231650-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/2380759.1783956175@warthog.procyon.org.uk
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

netfs: Replace wb_lock with a bit lock for asynchronicity

2026-07-01T13:26:29+00:00

The netfs_inode::wb_lock mutex is used to prevent multiple simultaneous
writebacks from fighting each other (a writeback thread will write multiple
discontiguous regions within the same request).  The mutex, however, only
serialises the issuing of subrequests; it doesn't serialise the collection
of results, and, in particular, the updating of file size information and
fscache populatedness data.

Unfortunately, the mutex cannot be held around the entire process as it has
to be unlocked in the same thread in which it is locked - and we don't want
to hold up the allocator whilst we complete the writeback.

Fix this by replacing the mutex with a bit flag and a list of lock waiters
so that the lock can be dropped in the collector thread after collection is
complete.

Link: https://sashiko.dev/#/patchset/20260608145432.681865-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260625140640.3116900-12-dhowells@redhat.com
cc: Paulo Alcantara 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Amutable)

afs: Fix unchecked-length string display in debug statement

2026-07-01T13:26:22+00:00

Fix afs_extract_vlserver_list() to limit the length of the displayed
string in a debug statement().

Fixes: 0a5143f2f89c ("afs: Implement VL server rotation")
Closes: https://sashiko.dev/#/patchset/20260618074903.2374756-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260622090856.2746629-22-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable)

afs: Fix the volume AFS_VOLUME_RM_TREE is set on

2026-07-01T13:26:22+00:00

Fix afs_insert_volume_into_cell() to set AFS_VOLUME_RM_TREE on the volume
replaced, not the new volume, as it's now removed from the cell's volume
tree.  This will cause the old volume to be removed from the tree twice and
the new volume never to be removed.

Fixes: 9a6b294ab496 ("afs: Fix use-after-free due to get/remove race in volume tree")
Closes: https://sashiko.dev/#/patchset/20260618074903.2374756-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260622090856.2746629-21-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable)

afs: Fix premature cell exposure through /afs

2026-07-01T13:26:22+00:00

AFS cell records are prematurely exposured through the /afs dynamic root by
virtue of adding them immediately to the net->cells_dyn_ino IDR when the
cell is allocated rather than when it is added to the lookup tree.  This
allows a candidate record to be accessed, even if it's actually a duplicate
or not published yet.

Fix this by not adding the cell to cells_dyn_ino until it's confirmed
non-duplicate and is being published.  A flag is then used to record
whether it is added to the IDR to make removal from the IDR conditional.

Closes: https://sashiko.dev/#/patchset/20260618155141.2513212-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260622090856.2746629-20-dhowells@redhat.com
Fixes: 1d0b929fc070 ("afs: Change dynroot to create contents on demand")
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable)

afs: Fix lack of locking around modifications of net->cells_dyn_ino

2026-07-01T13:26:21+00:00

Fix the lack of locking around modifications of net->cells_dyn_ino by
taking net->cells_lock exclusively.  This also requires to cell to be
removed from net->cells_dyn_ino in afs_destroy_cell_work() rather than in
afs_cell_destroy() as the latter runs in RCU cleanup context and sleeping
locks cannot be taken there.

Fixes: 1d0b929fc070 ("afs: Change dynroot to create contents on demand")
Closes: https://sashiko.dev/#/patchset/20260618074903.2374756-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260622090856.2746629-19-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable)

afs: Fix vllist leak

2026-07-01T13:26:21+00:00

Fix a leak of the new vllist in afs_update_cell() in the event that it is an
empty list (nr_servers == 0), in which case the old list isn't displaced
unless the old list is also empty.

Fixes: d5c32c89b208 ("afs: Fix cell DNS lookup")
Closes: https://sashiko.dev/#/patchset/20260609081738.770127-1-dhowells%40redhat.com
Signed-off-by: David Howells 
Link: https://patch.msgid.link/20260622090856.2746629-18-dhowells@redhat.com
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable)