http-backend: Fix access beyond end of string.

Found with valgrind while looking for Content-Length corruption in
smart http.

Signed-off-by: Tarmigan Casebolt <tarmigan+git@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/http-backend.c b/http-backend.c
index 7f48406d6dd8a3b67ade9a6b532a8c5764d61504..8e08f057dd6536b06d1ee017e4733ad1585e782e 100644 (file)
--- a/http-backend.c
+++ b/http-backend.c
@@ -615,7 +615,7 @@ int main(int argc, char **argv)
                if (regcomp(&re, c->pattern, REG_EXTENDED))
                        die("Bogus regex in service table: %s", c->pattern);
                if (!regexec(&re, dir, 1, out, 0)) {
-                       size_t n = out[0].rm_eo - out[0].rm_so;
+                       size_t n;
 
                        if (strcmp(method, c->method)) {
                                const char *proto = getenv("SERVER_PROTOCOL");
@@ -629,9 +629,10 @@ int main(int argc, char **argv)
                        }
 
                        cmd = c;
+                       n = out[0].rm_eo - out[0].rm_so;
                        cmd_arg = xmalloc(n);
-                       strncpy(cmd_arg, dir + out[0].rm_so + 1, n);
-                       cmd_arg[n] = '\0';
+                       memcpy(cmd_arg, dir + out[0].rm_so + 1, n-1);
+                       cmd_arg[n-1] = '\0';
                        dir[out[0].rm_so] = 0;
                        break;
                }