From 161f7a6f396152da50d18151c075fe9aba16c6db Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 15 Aug 2019 11:30:50 +0300 Subject: [PATCH] drm/vmwgfx: Fix double free in vmw_recv_msg() commit 08b0c891605acf727e43e3e03a25857d3e789b61 upstream. We recently added a kfree() after the end of the loop: if (retries == RETRIES) { kfree(reply); return -EINVAL; } There are two problems. First the test is wrong and because retries equals RETRIES if we succeed on the last iteration through the loop. Second if we fail on the last iteration through the loop then the kfree is a double free. When you're reading this code, please note the break statement at the end of the while loop. This patch changes the loop so that if it's not successful then "reply" is NULL and we can test for that afterward. Cc: Fixes: 6b7c3b86f0b6 ("drm/vmwgfx: fix memory leak when too many retries have occurred") Signed-off-by: Dan Carpenter Reviewed-by: Thomas Hellstrom Signed-off-by: Thomas Hellstrom Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/vmwgfx/vmwgfx_msg.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c index 77df50dd6d30..123d85de80d6 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c @@ -264,7 +264,7 @@ static int vmw_recv_msg(struct rpc_channel *channel, void **msg, if ((HIGH_WORD(ebx) & MESSAGE_STATUS_SUCCESS) == 0) { kfree(reply); - + reply = NULL; if ((HIGH_WORD(ebx) & MESSAGE_STATUS_CPT) != 0) { /* A checkpoint occurred. Retry. */ continue; @@ -288,7 +288,7 @@ static int vmw_recv_msg(struct rpc_channel *channel, void **msg, if ((HIGH_WORD(ecx) & MESSAGE_STATUS_SUCCESS) == 0) { kfree(reply); - + reply = NULL; if ((HIGH_WORD(ecx) & MESSAGE_STATUS_CPT) != 0) { /* A checkpoint occurred. Retry. */ continue; @@ -300,10 +300,8 @@ static int vmw_recv_msg(struct rpc_channel *channel, void **msg, break; } - if (retries == RETRIES) { - kfree(reply); + if (!reply) return -EINVAL; - } *msg_len = reply_len; *msg = reply;