[Asterisk-code-review] Astobj2: Correctly treat hash fn returning INT MIN (asterisk[13])

[Ivan Poddubny]

Ivan Poddubny has uploaded a new change for review.

  https://gerrit.asterisk.org/531

Change subject: Astobj2: Correctly treat hash_fn returning INT_MIN
......................................................................

Astobj2: Correctly treat hash_fn returning INT_MIN

The code in astobj2_hash.c wrongly assumed that abs(int) is always > 0.
However, abs(INT_MIN) = INT_MIN and is still negative, as well as
abs(INT_MIN) % num_buckets, and as a result this led to a crash.

One way to trigger the bug is using host=::80 or 0.0.0.128 in peer
configuration section in chan_sip or chan_iax.

This patch replaces usage of abs with casting to unsigned int for
calculating bucket number.

ASTERISK-25100 #close

Change-Id: Id6981400ad526f47e10bcf7b847b62bd2785e899
---
M main/astobj2_hash.c
1 file changed, 5 insertions(+), 6 deletions(-)


  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/31/531/1

diff --git a/main/astobj2_hash.c b/main/astobj2_hash.c
index 066999f..9f68381 100644
--- a/main/astobj2_hash.c
+++ b/main/astobj2_hash.c
@@ -235,8 +235,7 @@
 		return NULL;
 	}
 
-	i = abs(self->hash_fn(obj_new, OBJ_SEARCH_OBJECT));
-	i %= self->n_buckets;
+	i = (unsigned int)self->hash_fn(obj_new, OBJ_SEARCH_OBJECT) % self->n_buckets;
 
 	if (tag) {
 		__ao2_ref_debug(obj_new, +1, tag, file, line, func);
@@ -386,8 +385,8 @@
 	case OBJ_SEARCH_OBJECT:
 	case OBJ_SEARCH_KEY:
 		/* we know hash can handle this case */
-		bucket_cur = abs(self->hash_fn(arg, flags & OBJ_SEARCH_MASK));
-		bucket_cur %= self->n_buckets;
+		bucket_cur = (unsigned int)self->hash_fn(arg, flags & OBJ_SEARCH_MASK)
+			% self->n_buckets;
 		state->sort_fn = self->common.sort_fn;
 		break;
 	case OBJ_SEARCH_PARTIAL_KEY:
@@ -984,8 +983,8 @@
 			++count_obj;
 
 			/* Check container hash key for expected bucket. */
-			bucket_exp = abs(self->hash_fn(node->common.obj, OBJ_SEARCH_OBJECT));
-			bucket_exp %= self->n_buckets;
+			bucket_exp = (unsigned int)self->hash_fn(node->common.obj, OBJ_SEARCH_OBJECT)
+				% self->n_buckets;
 			if (bucket != bucket_exp) {
 				ast_log(LOG_ERROR, "Bucket %d node hashes to bucket %d!\n",
 					bucket, bucket_exp);

-- 
To view, visit https://gerrit.asterisk.org/531
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Id6981400ad526f47e10bcf7b847b62bd2785e899
Gerrit-PatchSet: 1
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Ivan Poddubny <ivan.poddubny at gmail.com>