linux-kernel - [PATCH 1/1] Properly check return values of kmalloc and vmbus

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Message-Id: <1291926209-17120-1-git-send-email-hjanssen@microsoft.com>
Date:	Thu,  9 Dec 2010 12:23:29 -0800
From:	Hank Janssen <hjanssen@...rosoft.com>
To:	hjanssen@...rosoft.com, zbr@...emap.net, gregkh@...e.de,
	linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
	virtualization@...ts.osdl.org
Cc:	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: [PATCH 1/1] Properly check return values of kmalloc and vmbus_recvpacket

Correct ugly oversight, we need to check the return values of kmalloc
and vmbus_recvpacket and return if they fail. I also tightened up the
call to kmalloc. 

Thanks to Evgeniy Polyakov <zbr@...emap.net>  for pointing this out.

Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
Signed-off-by: Hank Janssen <hjanssen@...rosoft.com>

---
 drivers/staging/hv/hv_utils.c |   48 ++++++++++++++++++++++++++++------------
 1 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/hv/hv_utils.c b/drivers/staging/hv/hv_utils.c
index 53e1e29..ac68575 100644
--- a/drivers/staging/hv/hv_utils.c
+++ b/drivers/staging/hv/hv_utils.c
@@ -43,21 +43,27 @@ static void shutdown_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u8 *buf;
-	u32 buflen, recvlen;
+	u32 recvlen;
 	u64 requestid;
 	u8  execute_shutdown = false;
+	int ret = 0;
 
 	struct shutdown_msg_data *shutdown_msg;
 
 	struct icmsg_hdr *icmsghdrp;
 	struct icmsg_negotiate *negop = NULL;
 
-	buflen = PAGE_SIZE;
-	buf = kmalloc(buflen, GFP_ATOMIC);
+	buf = kmalloc(PAGE_SIZE, GFP_ATOMIC);
 
-	vmbus_recvpacket(channel, buf, buflen, &recvlen, &requestid);
+	if (!buf) {
+		printk(KERN_INFO
+		       "Unable to allocate memory for shutdown_onchannelcallback");
+		return;
+	}
+
+	ret = vmbus_recvpacket(channel, buf, PAGE_SIZE, &recvlen, &requestid);
 
-	if (recvlen > 0) {
+	if (ret == 0 && recvlen > 0) {
 		DPRINT_DBG(VMBUS, "shutdown packet: len=%d, requestid=%lld",
 			   recvlen, requestid);
 
@@ -151,17 +157,23 @@ static void timesync_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u8 *buf;
-	u32 buflen, recvlen;
+	u32 recvlen;
 	u64 requestid;
 	struct icmsg_hdr *icmsghdrp;
 	struct ictimesync_data *timedatap;
+	int ret = 0;
 
-	buflen = PAGE_SIZE;
-	buf = kmalloc(buflen, GFP_ATOMIC);
+	buf = kmalloc(PAGE_SIZE, GFP_ATOMIC);
 
-	vmbus_recvpacket(channel, buf, buflen, &recvlen, &requestid);
+	if (!buf) {
+		printk(KERN_INFO
+		       "Unable to allocate memory for timesync_onchannelcallback");
+		return;
+	}
 
-	if (recvlen > 0) {
+	ret = vmbus_recvpacket(channel, buf, PAGE_SIZE, &recvlen, &requestid);
+
+	if (ret == 0 && recvlen > 0) {
 		DPRINT_DBG(VMBUS, "timesync packet: recvlen=%d, requestid=%lld",
 			recvlen, requestid);
 
@@ -197,17 +209,23 @@ static void heartbeat_onchannelcallback(void *context)
 {
 	struct vmbus_channel *channel = context;
 	u8 *buf;
-	u32 buflen, recvlen;
+	u32 recvlen;
 	u64 requestid;
 	struct icmsg_hdr *icmsghdrp;
 	struct heartbeat_msg_data *heartbeat_msg;
+	int ret = 0;
+
+	buf = kmalloc(PAGE_SIZE, GFP_ATOMIC);
 
-	buflen = PAGE_SIZE;
-	buf = kmalloc(buflen, GFP_ATOMIC);
+	if (!buf) {
+		printk(KERN_INFO
+		    "Unable to allocate memory for heartbeat_onchannelcallback");
+		return;
+	}
 
-	vmbus_recvpacket(channel, buf, buflen, &recvlen, &requestid);
+	ret = vmbus_recvpacket(channel, buf, PAGE_SIZE, &recvlen, &requestid);
 
-	if (recvlen > 0) {
+	if (ret == 0 && recvlen > 0) {
 		DPRINT_DBG(VMBUS, "heartbeat packet: len=%d, requestid=%lld",
 			   recvlen, requestid);
 
-- 
1.6.0.2

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