2018-07-31 14:04:32

by Colin King

Subject: [PATCH][next] xen/gntdev: don't dereference a null gntdev_dmabuf on allocation failure

From: Colin Ian King <[email protected]>

Currently when the allocation of gntdev_dmabuf fails, the error exit
path will call dmabuf_imp_free_storage and causes a null pointer
dereference on gntdev_dmabuf. Fix this by adding an error exit path
that won't free gntdev_dmabuf.

Detected by CoverityScan, CID#1472124 ("Dereference after null check")

Fixes: bf8dc55b1358 ("xen/gntdev: Implement dma-buf import functionality")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/xen/gntdev-dmabuf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index 744cfe9b0311..cba6b586bfbd 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -568,7 +568,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)

gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
if (!gntdev_dmabuf)
- goto fail;
+ goto fail_no_free;

gntdev_dmabuf->u.imp.refs = kcalloc(count,
sizeof(gntdev_dmabuf->u.imp.refs[0]),
@@ -591,6 +591,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)

fail:
dmabuf_imp_free_storage(gntdev_dmabuf);
+fail_no_free:
return ERR_PTR(-ENOMEM);
}

--
2.17.1

2018-07-31 17:10:03

by Boris Ostrovsky

Subject: Re: [PATCH][next] xen/gntdev: don't dereference a null gntdev_dmabuf on allocation failure

On 07/31/2018 10:02 AM, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> Currently when the allocation of gntdev_dmabuf fails, the error exit
> path will call dmabuf_imp_free_storage and causes a null pointer
> dereference on gntdev_dmabuf. Fix this by adding an error exit path
> that won't free gntdev_dmabuf.
>
> Detected by CoverityScan, CID#1472124 ("Dereference after null check")
>
> Fixes: bf8dc55b1358 ("xen/gntdev: Implement dma-buf import functionality")
> Signed-off-by: Colin Ian King <[email protected]>

Reviewed-by: Boris Ostrovsky <[email protected]>

Applied to for-linus-4.19.



> ---
> drivers/xen/gntdev-dmabuf.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
> index 744cfe9b0311..cba6b586bfbd 100644
> --- a/drivers/xen/gntdev-dmabuf.c
> +++ b/drivers/xen/gntdev-dmabuf.c
> @@ -568,7 +568,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
>
> gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
> if (!gntdev_dmabuf)
> - goto fail;
> + goto fail_no_free;
>
> gntdev_dmabuf->u.imp.refs = kcalloc(count,
> sizeof(gntdev_dmabuf->u.imp.refs[0]),
> @@ -591,6 +591,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
>
> fail:
> dmabuf_imp_free_storage(gntdev_dmabuf);
> +fail_no_free:
> return ERR_PTR(-ENOMEM);
> }
>