From 5aca48b16e7212a20b0ff850b1ca7afb431dabf1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C5=8Dshin?= <git@wholezero.org>
Date: Mon, 18 Dec 2023 22:46:07 -0500
Subject: [PATCH] Fix buffer overflow in TryPath

Missed this when changing the code back to be like the old version.
com is now a parameter.

The only plausible way to trigger this would be to pass a loader
pathname close to MAX_PATH characters long, and then remove that
path prior to the first sys_faccessat.
---
 libc/calls/getprogramexecutablename.greg.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libc/calls/getprogramexecutablename.greg.c b/libc/calls/getprogramexecutablename.greg.c
index 17d270ad4..5d3c576b5 100644
--- a/libc/calls/getprogramexecutablename.greg.c
+++ b/libc/calls/getprogramexecutablename.greg.c
@@ -98,6 +98,7 @@ static int TryPath(const char *q, int com) {
   }
   *p = 0;
   if (!sys_faccessat(AT_FDCWD, g_prog.u.buf, F_OK, 0)) return 1;
+  if (!com) return 0;
   p = WRITE32LE(p, READ32LE(".com"));
   *p = 0;
   if (!sys_faccessat(AT_FDCWD, g_prog.u.buf, F_OK, 0)) return 1;