From: Schspa Shi <schspa@gmail.com>
Date: Wed, 29 Jun 2022 02:29:48 +0000 (+0800)
Subject: vfio: Clear the caps->buf to NULL after free
X-Git-Tag: v5.10.138~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5e034e03f416242bb8272bd3866a93281bbfcb24;p=thirdparty%2Fkernel%2Fstable.git

vfio: Clear the caps->buf to NULL after free

[ Upstream commit 6641085e8d7b3f061911517f79a2a15a0a21b97b ]

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 <schspa@gmail.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/20220629022948.55608-1-schspa@gmail.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index f886f2db8153e..90db9d66867c7 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1783,6 +1783,7 @@ 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);
 	}