gc: do not explode objects which will be immediately pruned

diff --git a/hex.c b/hex.c
index bb402fbaa2a04ef0849789fdd814dcbb8773fff5..9ebc050637532765b775cbd8e3b92951a67ea333 100644 (file)
--- a/hex.c
+++ b/hex.c
@@ -39,7 +39,15 @@ int get_sha1_hex(const char *hex, unsigned char *sha1)
 {
        int i;
        for (i = 0; i < 20; i++) {
-               unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
+               unsigned int val;
+               /*
+                * hex[1]=='\0' is caught when val is checked below,
+                * but if hex[0] is NUL we have to avoid reading
+                * past the end of the string:
+                */
+               if (!hex[0])
+                       return -1;
+               val = (hexval(hex[0]) << 4) | hexval(hex[1]);
                if (val & ~0xff)
                        return -1;
                *sha1++ = val;