rps: fix insufficient bounds checking in store_rps_dev_flow_table_cnt()
authorXi Wang <xi.wang@gmail.com>
Thu, 22 Dec 2011 13:35:22 +0000 (13:35 +0000)
committerDavid S. Miller <davem@davemloft.net>
Fri, 23 Dec 2011 03:34:56 +0000 (22:34 -0500)
Setting a large rps_flow_cnt like (1 << 30) on 32-bit platform will
cause a kernel oops due to insufficient bounds checking.

if (count > 1<<30) {
/* Enforce a limit to prevent overflow */
return -EINVAL;
}
count = roundup_pow_of_two(count);
table = vmalloc(RPS_DEV_FLOW_TABLE_SIZE(count));

Note that the macro RPS_DEV_FLOW_TABLE_SIZE(count) is defined as:

... + (count * sizeof(struct rps_dev_flow))

where sizeof(struct rps_dev_flow) is 8.  (1 << 30) * 8 will overflow
32 bits.

This patch replaces the magic number (1 << 30) with a symbolic bound.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/core/net-sysfs.c

index c71c434a4c053e440dc816682d944c521e05c50f..385aefe536489548ed3f53e61094faaac0d08afd 100644 (file)
@@ -665,11 +665,14 @@ static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,
        if (count) {
                int i;
 
-               if (count > 1<<30) {
+               if (count > INT_MAX)
+                       return -EINVAL;
+               count = roundup_pow_of_two(count);
+               if (count > (ULONG_MAX - sizeof(struct rps_dev_flow_table))
+                               / sizeof(struct rps_dev_flow)) {
                        /* Enforce a limit to prevent overflow */
                        return -EINVAL;
                }
-               count = roundup_pow_of_two(count);
                table = vmalloc(RPS_DEV_FLOW_TABLE_SIZE(count));
                if (!table)
                        return -ENOMEM;