[PATCH v2] block/bio-integrity: fix a memory leak bug

[PATCH v2] block/bio-integrity: fix a memory leak bug

[Wenwen Wang]

From: Wenwen Wang <wenwen@cs.uga.edu>

In bio_integrity_prep(), a kernel buffer is allocated through kmalloc() to
hold integrity metadata. Later on, the buffer will be attached to the bio
structure through bio_integrity_add_page(), which returns the number of
bytes of integrity metadata attached. Due to unexpected situations,
bio_integrity_add_page() may return 0. As a result, bio_integrity_prep()
needs to be terminated with 'false' returned to indicate this error.
However, the allocated kernel buffer is not freed on this execution path,
leading to a memory leak.

To fix this issue, free the allocated buffer before returning from
bio_integrity_prep().

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
---
 block/bio-integrity.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index 4db6208..fb95dbb 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -276,8 +276,12 @@ bool bio_integrity_prep(struct bio *bio)
 		ret = bio_integrity_add_page(bio, virt_to_page(buf),
 					     bytes, offset);
 
-		if (ret == 0)
-			return false;
+		if (ret == 0) {
+			printk(KERN_ERR "could not attach integrity payload\n");
+			kfree(buf);
+			status = BLK_STS_RESOURCE;
+			goto err_end_io;
+		}
 
 		if (ret < bytes)
 			break;
-- 
2.7.4

Re: [PATCH v2] block/bio-integrity: fix a memory leak bug

[Ming Lei]

On Fri, Jul 12, 2019 at 3:29 AM Wenwen Wang <wang6495@umn.edu> wrote:
>
> From: Wenwen Wang <wenwen@cs.uga.edu>
>
> In bio_integrity_prep(), a kernel buffer is allocated through kmalloc() to
> hold integrity metadata. Later on, the buffer will be attached to the bio
> structure through bio_integrity_add_page(), which returns the number of
> bytes of integrity metadata attached. Due to unexpected situations,
> bio_integrity_add_page() may return 0. As a result, bio_integrity_prep()
> needs to be terminated with 'false' returned to indicate this error.
> However, the allocated kernel buffer is not freed on this execution path,
> leading to a memory leak.
>
> To fix this issue, free the allocated buffer before returning from
> bio_integrity_prep().
>
> Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
> ---
>  block/bio-integrity.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/block/bio-integrity.c b/block/bio-integrity.c
> index 4db6208..fb95dbb 100644
> --- a/block/bio-integrity.c
> +++ b/block/bio-integrity.c
> @@ -276,8 +276,12 @@ bool bio_integrity_prep(struct bio *bio)
>                 ret = bio_integrity_add_page(bio, virt_to_page(buf),
>                                              bytes, offset);
>
> -               if (ret == 0)
> -                       return false;
> +               if (ret == 0) {
> +                       printk(KERN_ERR "could not attach integrity payload\n");
> +                       kfree(buf);
> +                       status = BLK_STS_RESOURCE;
> +                       goto err_end_io;
> +               }
>
>                 if (ret < bytes)
>                         break;

Looks fine:

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming Lei

Re: [PATCH v2] block/bio-integrity: fix a memory leak bug

[Martin K. Petersen]

Wenwen,

> To fix this issue, free the allocated buffer before returning from
> bio_integrity_prep().

Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH v2] block/bio-integrity: fix a memory leak bug

[Jens Axboe]

On 7/11/19 1:22 PM, Wenwen Wang wrote:
> From: Wenwen Wang <wenwen@cs.uga.edu>
> 
> In bio_integrity_prep(), a kernel buffer is allocated through kmalloc() to
> hold integrity metadata. Later on, the buffer will be attached to the bio
> structure through bio_integrity_add_page(), which returns the number of
> bytes of integrity metadata attached. Due to unexpected situations,
> bio_integrity_add_page() may return 0. As a result, bio_integrity_prep()
> needs to be terminated with 'false' returned to indicate this error.
> However, the allocated kernel buffer is not freed on this execution path,
> leading to a memory leak.
> 
> To fix this issue, free the allocated buffer before returning from
> bio_integrity_prep().

Applied, thanks.

-- 
Jens Axboe