Commit 09930192b903e15d5c55afc2fd83d6f37ba6edd9
2017-08-09T16:34:02
sha1_position: convert do-while to while If we enter the sha1_position() function with "lo == hi", we have no elements. But the do-while loop means that we'll enter the loop body once anyway, picking "mi" at that same value and comparing nonsense to our desired key. This is unlikely to match in practice, but we still shouldn't be looking at the memory in the first place. This bug is inherited from git.git; it was fixed there in e01580cfe01526ec2c4eb4899f776a82ade7e0e1.
diff --git a/src/sha1_lookup.c b/src/sha1_lookup.c
index ead26de..60a7444 100644
--- a/src/sha1_lookup.c
+++ b/src/sha1_lookup.c
@@ -232,7 +232,7 @@ int sha1_position(const void *table,
{
const unsigned char *base = table;
- do {
+ while (lo < hi) {
unsigned mi = (lo + hi) / 2;
int cmp = git_oid__hashcmp(base + mi * stride, key);
@@ -243,7 +243,7 @@ int sha1_position(const void *table,
hi = mi;
else
lo = mi+1;
- } while (lo < hi);
+ }
return -((int)lo)-1;
}