* [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
* [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
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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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