Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Schspa Shi <schspa@gmail.com>, Cornelia Huck <cohuck@redhat.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Sasha Levin <sashal@kernel.org>, kvm@vger.kernel.org
Subject: [PATCH AUTOSEL 5.15 04/28] vfio: Clear the caps->buf to NULL after free
Date:   Sun, 14 Aug 2022 12:25:44 -0400
Message-Id: <20220814162610.2397644-4-sashal@kernel.org>
In-Reply-To: <20220814162610.2397644-1-sashal@kernel.org>
References: <20220814162610.2397644-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Schspa Shi <schspa@gmail.com>

[ 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>
---
 drivers/vfio/vfio.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 3c034fe14ccb..818e47fc0896 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1850,6 +1850,7 @@ 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);
 	}
-- 
2.35.1