fib_trie: Address possible NULL pointer dereference in resize (ddb4b9a1) · Commits · 戴 / test

If the inflate call failed it would return NULL. As a result tp would be set to NULL and cause use to trigger a NULL pointer dereference in should_halve if the inflate failed on the first attempt. In order to prevent this we should decrement max_work before we actually attempt to inflate as this will force us to exit before attempting to halve a node we should have inflated. In order to keep things symmetric between inflate and halve I went ahead and also moved the decrement of max_work for the halve case as well so we take care of that before we actually attempt to halve the tnode. Fixes: ("fib_trie: Add key vector to root, return parent key_vector in resize") Reported-by:

Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:

Alexander Duyck <alexander.h.duyck@redhat.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/ipv4/fib_trie.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -830,7 +830,7 @@ static struct key_vector resize(struct trie t, struct key_vector *tn)
		/* Double as long as the resulting node has a number of
		* nonempty nodes that are above the threshold.
		*/
		while (should_inflate(tp, tn) && max_work) {
		while (should_inflate(tp, tn) && max_work--) {
		tp = inflate(t, tn);
		if (!tp) {
		#ifdef CONFIG_IP_FIB_TRIE_STATS
		@@ -839,7 +839,6 @@ static struct key_vector resize(struct trie t, struct key_vector *tn)
		break;
		}

		max_work--;
		tn = get_child(tp, cindex);
		}

		@@ -850,7 +849,7 @@ static struct key_vector resize(struct trie t, struct key_vector *tn)
		/* Halve as long as the number of empty children in this
		* node is above threshold.
		*/
		while (should_halve(tp, tn) && max_work) {
		while (should_halve(tp, tn) && max_work--) {
		tp = halve(t, tn);
		if (!tp) {
		#ifdef CONFIG_IP_FIB_TRIE_STATS
		@@ -859,7 +858,6 @@ static struct key_vector resize(struct trie t, struct key_vector *tn)
		break;
		}

		max_work--;
		tn = get_child(tp, cindex);
		}

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