24c04c
From ad3a19e6372b1e667128ed1ea2f49919884587e1 Mon Sep 17 00:00:00 2001
24c04c
From: Akira TAGOH <akira@tagoh.org>
24c04c
Date: Thu, 17 Feb 2022 17:30:12 +0900
24c04c
Subject: [PATCH 1/4] Fix the stack buffer overflow issue
24c04c
24c04c
strlen() could returns 0. Without a conditional check for len,
24c04c
accessing S_ pointer with len - 1 may causes a stack buffer overflow.
24c04c
24c04c
AddressSanitizer reports this like:
24c04c
==1219243==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffdce043c1f at pc 0x000000403547 bp 0x7ffdce0
24c04c
43b30 sp 0x7ffdce043b28
24c04c
READ of size 1 at 0x7ffdce043c1f thread T0
24c04c
    #0 0x403546 in main ../bin/fribidi-main.c:393
24c04c
    #1 0x7f226804e58f in __libc_start_call_main (/lib64/libc.so.6+0x2d58f)
24c04c
    #2 0x7f226804e648 in __libc_start_main_impl (/lib64/libc.so.6+0x2d648)
24c04c
    #3 0x4036f4 in _start (/tmp/fribidi/build/bin/fribidi+0x4036f4)
24c04c
24c04c
Address 0x7ffdce043c1f is located in stack of thread T0 at offset 63 in frame
24c04c
    #0 0x4022bf in main ../bin/fribidi-main.c:193
24c04c
24c04c
  This frame has 5 object(s):
24c04c
    [32, 36) 'option_index' (line 233)
24c04c
    [48, 52) 'base' (line 386)
24c04c
    [64, 65064) 'S_' (line 375) <== Memory access at offset 63 underflows this variable
24c04c
    [65328, 130328) 'outstring' (line 385)
24c04c
    [130592, 390592) 'logical' (line 384)
24c04c
24c04c
This fixes https://github.com/fribidi/fribidi/issues/181
24c04c
---
24c04c
 bin/fribidi-main.c | 2 +-
24c04c
 1 file changed, 1 insertion(+), 1 deletion(-)
24c04c
24c04c
diff --git a/bin/fribidi-main.c b/bin/fribidi-main.c
24c04c
index 3cf9fe1..3ae4fb6 100644
24c04c
--- a/bin/fribidi-main.c
24c04c
+++ b/bin/fribidi-main.c
24c04c
@@ -390,7 +390,7 @@ FRIBIDI_END_IGNORE_DEPRECATIONS
24c04c
 	    S_[sizeof (S_) - 1] = 0;
24c04c
 	    len = strlen (S_);
24c04c
 	    /* chop */
24c04c
-	    if (S_[len - 1] == '\n')
24c04c
+	    if (len > 0 && S_[len - 1] == '\n')
24c04c
 	      {
24c04c
 		len--;
24c04c
 		S_[len] = '\0';
24c04c
-- 
24c04c
2.35.1
24c04c