* [PATCH] netfs: Fix AIO error handling when doing write-through
@ 2024-05-21 13:36 David Howells
2024-05-21 14:16 ` Christian Brauner
0 siblings, 1 reply; 2+ messages in thread
From: David Howells @ 2024-05-21 13:36 UTC (permalink / raw
To: Steve French
Cc: dhowells, Jeff Layton, Enzo Matsumiya, Christian Brauner, netfs,
v9fs, linux-afs, linux-cifs, linux-fsdevel, linux-kernel
If an error occurs whilst we're doing an AIO write in write-through mode,
we may end up calling ->ki_complete() *and* returning an error from
->write_iter(). This can result in either a UAF (the ->ki_complete() func
pointer may get overwritten, for example) or a refcount underflow in
io_submit() as ->ki_complete is called twice.
Fix this by making netfs_end_writethrough() - and thus
netfs_perform_write() - unconditionally return -EIOCBQUEUED if we're doing
an AIO write and wait for completion if we're not.
Fixes: 288ace2f57c9 ("netfs: New writeback implementation")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: netfs@lists.linux.dev
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
fs/netfs/write_issue.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index e190043bc0da..acbfd1f5ee9d 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -636,7 +636,12 @@ int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_contr
mutex_unlock(&ictx->wb_lock);
- ret = wreq->error;
+ if (wreq->iocb) {
+ ret = -EIOCBQUEUED;
+ } else {
+ wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS, TASK_UNINTERRUPTIBLE);
+ ret = wreq->error;
+ }
netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
return ret;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] netfs: Fix AIO error handling when doing write-through
2024-05-21 13:36 [PATCH] netfs: Fix AIO error handling when doing write-through David Howells
@ 2024-05-21 14:16 ` Christian Brauner
0 siblings, 0 replies; 2+ messages in thread
From: Christian Brauner @ 2024-05-21 14:16 UTC (permalink / raw
To: Steve French, David Howells
Cc: Christian Brauner, Jeff Layton, Enzo Matsumiya, netfs, v9fs,
linux-afs, linux-cifs, linux-fsdevel, linux-kernel
On Tue, 21 May 2024 14:36:27 +0100, David Howells wrote:
> If an error occurs whilst we're doing an AIO write in write-through mode,
> we may end up calling ->ki_complete() *and* returning an error from
> ->write_iter(). This can result in either a UAF (the ->ki_complete() func
> pointer may get overwritten, for example) or a refcount underflow in
> io_submit() as ->ki_complete is called twice.
>
> Fix this by making netfs_end_writethrough() - and thus
> netfs_perform_write() - unconditionally return -EIOCBQUEUED if we're doing
> an AIO write and wait for completion if we're not.
>
> [...]
Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.
Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes
[1/1] netfs: Fix AIO error handling when doing write-through
https://git.kernel.org/vfs/vfs/c/eb5239732070
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