2021-09-03 12:03:34

by Colin King

Subject: [PATCH][next] io_uring: Fix a read of ununitialized pointer tctx

From: Colin Ian King <[email protected]>

In the unlikely case where ctx->flags & IORING_SETUP_SQPOLL is true
and sqd is NULL the pointer tctx is not assigned a valid value and
can contain a garbage value when it is dereferenced. Fix this by
initializing it to NULL.

Addresses-Coverity: ("Uninitialized pointer read")
Fixes: 9e30726065ea ("io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL")
Signed-off-by: Colin Ian King <[email protected]>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 132dd38e89ce..843362bebd8c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -10525,7 +10525,7 @@ static int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
void __user *arg)
{
struct io_sq_data *sqd = NULL;
- struct io_uring_task *tctx;
+ struct io_uring_task *tctx = NULL;
__u32 new_count[2];
int i, ret;

--
2.32.0

2021-09-03 13:10:27

by Jens Axboe

Subject: Re: [PATCH][next] io_uring: Fix a read of ununitialized pointer tctx

On 9/3/21 5:35 AM, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> In the unlikely case where ctx->flags & IORING_SETUP_SQPOLL is true
> and sqd is NULL the pointer tctx is not assigned a valid value and
> can contain a garbage value when it is dereferenced. Fix this by
> initializing it to NULL.

Doh - thanks, I folded this one in.

--
Jens Axboe