From: Alexander Duyck Date: Tue, 10 Mar 2015 21:39:34 +0000 (-0700) Subject: fib_trie: Address possible NULL pointer dereference in resize X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ddb4b9a1328ea89733133e86cf1972d23891abfc;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git fib_trie: Address possible NULL pointer dereference in resize 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: 88bae714 ("fib_trie: Add key vector to root, return parent key_vector in resize") Reported-by: Dan Carpenter Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 44cab1d41463..83290beaf7cf 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -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); }