Commit ddb4b9a1 authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller

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: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 416377ea
...@@ -830,7 +830,7 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn) ...@@ -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 /* Double as long as the resulting node has a number of
* nonempty nodes that are above the threshold. * 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); tp = inflate(t, tn);
if (!tp) { if (!tp) {
#ifdef CONFIG_IP_FIB_TRIE_STATS #ifdef CONFIG_IP_FIB_TRIE_STATS
...@@ -839,7 +839,6 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn) ...@@ -839,7 +839,6 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn)
break; break;
} }
max_work--;
tn = get_child(tp, cindex); tn = get_child(tp, cindex);
} }
...@@ -850,7 +849,7 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn) ...@@ -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 /* Halve as long as the number of empty children in this
* node is above threshold. * node is above threshold.
*/ */
while (should_halve(tp, tn) && max_work) { while (should_halve(tp, tn) && max_work--) {
tp = halve(t, tn); tp = halve(t, tn);
if (!tp) { if (!tp) {
#ifdef CONFIG_IP_FIB_TRIE_STATS #ifdef CONFIG_IP_FIB_TRIE_STATS
...@@ -859,7 +858,6 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn) ...@@ -859,7 +858,6 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn)
break; break;
} }
max_work--;
tn = get_child(tp, cindex); tn = get_child(tp, cindex);
} }
......
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