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| author | Hagar Hemdan <hagarhem@amazon.com> | 2024-06-04 13:05:27 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-11-17 15:07:21 +0100 |
| commit | fdacd09f2ddf7a00787291f08ee48c0421e5b709 (patch) | |
| tree | f4e027d78044ef4bdf05545680e30353ae98ac2d /io_uring | |
| parent | 9478355c63099f1fb0b0674d74a402933c0d8f7f (diff) | |
| download | linux-fdacd09f2ddf7a00787291f08ee48c0421e5b709.tar.gz linux-fdacd09f2ddf7a00787291f08ee48c0421e5b709.tar.bz2 linux-fdacd09f2ddf7a00787291f08ee48c0421e5b709.zip | |
io_uring: fix possible deadlock in io_register_iowq_max_workers()
commit 73254a297c2dd094abec7c9efee32455ae875bdf upstream.
The io_register_iowq_max_workers() function calls io_put_sq_data(),
which acquires the sqd->lock without releasing the uring_lock.
Similar to the commit 009ad9f0c6ee ("io_uring: drop ctx->uring_lock
before acquiring sqd->lock"), this can lead to a potential deadlock
situation.
To resolve this issue, the uring_lock is released before calling
io_put_sq_data(), and then it is re-acquired after the function call.
This change ensures that the locks are acquired in the correct
order, preventing the possibility of a deadlock.
Suggested-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>
Link: https://lore.kernel.org/r/20240604130527.3597-1-hagarhem@amazon.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 92c1aa8f3501..4f0ae938b146 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3921,8 +3921,10 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx, } if (sqd) { + mutex_unlock(&ctx->uring_lock); mutex_unlock(&sqd->lock); io_put_sq_data(sqd); + mutex_lock(&ctx->uring_lock); } if (copy_to_user(arg, new_count, sizeof(new_count))) @@ -3947,8 +3949,11 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx, return 0; err: if (sqd) { + mutex_unlock(&ctx->uring_lock); mutex_unlock(&sqd->lock); io_put_sq_data(sqd); + mutex_lock(&ctx->uring_lock); + } return ret; } |