From: Mark Wielaard <mark@klomp.org>
Date: Sat, 4 Dec 2021 12:07:04 +0000 (+0100)
Subject: debuginfod: sqlite3_sharedprefix_fn should not compare past end of string
X-Git-Tag: elfutils-0.187~81
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=32ceb411faec6ca61ee04707fe014efa15e9a5df;p=thirdparty%2Felfutils.git

debuginfod: sqlite3_sharedprefix_fn should not compare past end of string

gcc address sanitizer detected a read after the end of string in
sqlite3_sharedprefix_fn. Make sure to stop comparing the strings when
seeing the zero terminator.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---

diff --git a/debuginfod/debuginfod.cxx b/debuginfod/debuginfod.cxx
index 0bbaae9fd..0d3f02978 100644
--- a/debuginfod/debuginfod.cxx
+++ b/debuginfod/debuginfod.cxx
@@ -3707,7 +3707,7 @@ static void sqlite3_sharedprefix_fn (sqlite3_context* c, int argc, sqlite3_value
       const unsigned char* a = sqlite3_value_text (argv[0]);
       const unsigned char* b = sqlite3_value_text (argv[1]);
       int i = 0;
-      while (*a++ == *b++)
+      while (*a != '\0' && *b != '\0' && *a++ == *b++)
         i++;
       sqlite3_result_int (c, i);
     }