2022-06-29 03:11:55

by Schspa Shi

Subject: [PATCH v3] vfio: Clear the caps->buf to NULL after free

On buffer resize failure, vfio_info_cap_add() will free the buffer,
report zero for the size, and return -ENOMEM. As additional
hardening, also clear the buffer pointer to prevent any chance of a
double free.

Signed-off-by: Schspa Shi <[email protected]>

--

Changelog:
v1 -> v2:
- Remove incorrect double free report in commit message.
v2 -> v3:
- Update commit comment as Alex advised.
---
drivers/vfio/vfio.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 61e71c1154be..a0fb93866f61 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1812,6 +1812,7 @@ struct vfio_info_cap_header *vfio_info_cap_add(struct vfio_info_cap *caps,
buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL);
if (!buf) {
kfree(caps->buf);
+ caps->buf = NULL;
caps->size = 0;
return ERR_PTR(-ENOMEM);
}
--
2.29.0

2022-06-30 20:37:21

by Alex Williamson

Subject: Re: [PATCH v3] vfio: Clear the caps->buf to NULL after free

On Wed, 29 Jun 2022 10:29:48 +0800
Schspa Shi <[email protected]> wrote:

> On buffer resize failure, vfio_info_cap_add() will free the buffer,
> report zero for the size, and return -ENOMEM. As additional
> hardening, also clear the buffer pointer to prevent any chance of a
> double free.
>
> Signed-off-by: Schspa Shi <[email protected]>
>

Applied to vfio next branch for v5.20. Thanks,

Alex