fuse-uring: make a fuse_req on SQE commit only findable after memcpy

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Bad userspace might try to trick us and send commit SQEs request
unique / commit-id of requests that are not even send to
fuse-server (io_uring_cmd_done() not called) yet.

fuse_uring_commit_fetch() ends the fuse request when the ring entry
has a wrong state, but that could have caused a use-after-free
with the memcpy operations in fuse_uring_send_in_task().
In order to avoid such races the call of fuse_uring_add_to_pq()
is moved after the copy operations and just before completing
the io-uring request - malicious userspace cannot find the request
anymore until all prepration work in fuse-client/kernel is completed.

This also moves fuse_uring_add_to_pq() a bit up in the code to
avoid a forward declaration. Also not with a preparation commit,
to make it easier to back port to older kernels.

Reported-by: xlabai <xlabai@tencent.com>
Reported-by: Berkant Koc <me@berkoc.com>
Fixes: c090c8abae ("fuse: Add io-uring sqe commit and fetch support")
Cc: stable@kernel.org # 6.14
Signed-off-by: Bernd Schubert <bernd@bsbernd.com>
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

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This commit is contained in:

Bernd Schubert 2026-06-08 23:03:45 +02:00 • committed by Miklos Szeredi

parent b70a3aca16

commit 1efd3d474f

1 changed files with 19 additions and 14 deletions

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fs/fuse/dev_uring.c

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