Commit a0a129f8 authored Dec 22, 2011 by Xi Wang Committed by David S. Miller Dec 22, 2011

rps: fix insufficient bounds checking in store_rps_dev_flow_table_cnt()



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>

parent e688a604

net/core/net-sysfs.c

+5 −2

Original line number	Original line	Diff line number	Diff line
	@@ -665,11 +665,14 @@ static ssize_t store_rps_dev_flow_table_cnt(struct netdev_rx_queue *queue,
	if (count) {		if (count) {
	int i;		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 */		/* Enforce a limit to prevent overflow */
	return -EINVAL;		return -EINVAL;
	}		}
	count = roundup_pow_of_two(count);
	table = vmalloc(RPS_DEV_FLOW_TABLE_SIZE(count));		table = vmalloc(RPS_DEV_FLOW_TABLE_SIZE(count));
	if (!table)		if (!table)
	return -ENOMEM;		return -ENOMEM;