* [PATCH AUTOSEL 6.9 36/44] io_uring: fix possible deadlock in io_register_iowq_max_workers() [not found] <[email protected]> @ 2024-06-18 12:35 ` Sasha Levin 0 siblings, 0 replies; 2+ messages in thread From: Sasha Levin @ 2024-06-18 12:35 UTC (permalink / raw) To: linux-kernel, stable Cc: Hagar Hemdan, Maximilian Heyne, Jens Axboe, Sasha Levin, io-uring From: Hagar Hemdan <[email protected]> [ Upstream commit 73254a297c2dd094abec7c9efee32455ae875bdf ] 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 <[email protected]> Signed-off-by: Hagar Hemdan <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- io_uring/register.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/io_uring/register.c b/io_uring/register.c index 99c37775f974c..1ae8491e35abb 100644 --- a/io_uring/register.c +++ b/io_uring/register.c @@ -355,8 +355,10 @@ 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))) @@ -381,8 +383,10 @@ 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; } -- 2.43.0 ^ permalink raw reply related [flat|nested] 2+ messages in thread
[parent not found: <[email protected]>]* [PATCH AUTOSEL 6.9 36/44] io_uring: fix possible deadlock in io_register_iowq_max_workers() [not found] <[email protected]> @ 2024-06-17 13:19 ` Sasha Levin 0 siblings, 0 replies; 2+ messages in thread From: Sasha Levin @ 2024-06-17 13:19 UTC (permalink / raw) To: linux-kernel, stable Cc: Hagar Hemdan, Maximilian Heyne, Jens Axboe, Sasha Levin, io-uring From: Hagar Hemdan <[email protected]> [ Upstream commit 73254a297c2dd094abec7c9efee32455ae875bdf ] 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 <[email protected]> Signed-off-by: Hagar Hemdan <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- io_uring/register.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/io_uring/register.c b/io_uring/register.c index 99c37775f974c..1ae8491e35abb 100644 --- a/io_uring/register.c +++ b/io_uring/register.c @@ -355,8 +355,10 @@ 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))) @@ -381,8 +383,10 @@ 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; } -- 2.43.0 ^ permalink raw reply related [flat|nested] 2+ messages in thread
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2024-06-18 12:35 ` [PATCH AUTOSEL 6.9 36/44] io_uring: fix possible deadlock in io_register_iowq_max_workers() Sasha Levin
[not found] <[email protected]>
2024-06-17 13:19 ` Sasha Levin
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