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| author | Pavel Begunkov <asml.silence@gmail.com> | 2021-05-14 13:02:50 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-05-14 14:06:15 +0200 |
| commit | 447c19f3b5074409c794b350b10306e1da1ef4ba (patch) | |
| tree | 5839f4dfe4998bd3ddee091dc23c2fe4fb8d9427 /fs/io_uring.c | |
| parent | io_uring: fix link timeout refs (diff) | |
| download | linux-447c19f3b5074409c794b350b10306e1da1ef4ba.tar.xz linux-447c19f3b5074409c794b350b10306e1da1ef4ba.zip | |
io_uring: fix ltout double free on completion race
Always remove linked timeout on io_link_timeout_fn() from the master
request link list, otherwise we may get use-after-free when first
io_link_timeout_fn() puts linked timeout in the fail path, and then
will be found and put on master's free.
Cc: stable@vger.kernel.org # 5.10+
Fixes: 90cd7e424969d ("io_uring: track link timeout's master explicitly")
Reported-and-tested-by: syzbot+5a864149dd970b546223@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/69c46bf6ce37fec4fdcd98f0882e18eb07ce693a.1620990121.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to '')
| -rw-r--r-- | fs/io_uring.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 9ac5e278a91e..599102cc6dfc 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6354,10 +6354,11 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) * We don't expect the list to be empty, that will only happen if we * race with the completion of the linked work. */ - if (prev && req_ref_inc_not_zero(prev)) + if (prev) { io_remove_next_linked(prev); - else - prev = NULL; + if (!req_ref_inc_not_zero(prev)) + prev = NULL; + } spin_unlock_irqrestore(&ctx->completion_lock, flags); if (prev) { |