[PATCH][next] io_uring: fix incorrect check for kvmalloc failure

[PATCH][next] io_uring: fix incorrect check for kvmalloc failure

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently imu is being allocated but the kvmalloc failure is checking
imu->bvec instead of imu.  Fix this by checking imu for null.

Addresses-Coverity: ("Array compared against 0")
Fixes: 41edf1a5ec96 ("io_uring: keep table of pointers to ubufs")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 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 57a64c7e0e69..f4ec092c23f4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8269,7 +8269,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
 		goto done;
 
 	imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL);
-	if (!imu->bvec)
+	if (!imu)
 		goto done;
 
 	ret = 0;
-- 
2.30.2

Re: [PATCH][next] io_uring: fix incorrect check for kvmalloc failure

[Pavel Begunkov]

On 4/26/21 10:37 AM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Currently imu is being allocated but the kvmalloc failure is checking
> imu->bvec instead of imu.  Fix this by checking imu for null.

Right, that's buggy.

fwiw, was reported by lkp and I sent a fix yesterday, so take any.
https://lore.kernel.org/io-uring/d28eb1bc4384284f69dbce35b9f70c115ff6176f.1619392565.git.asml.silence@gmail.com/T/#u


> 
> Addresses-Coverity: ("Array compared against 0")
> Fixes: 41edf1a5ec96 ("io_uring: keep table of pointers to ubufs")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  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 57a64c7e0e69..f4ec092c23f4 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -8269,7 +8269,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
>  		goto done;
>  
>  	imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL);
> -	if (!imu->bvec)
> +	if (!imu)
>  		goto done;
>  
>  	ret = 0;
> 

-- 
Pavel Begunkov