| https://github.com/gentoo/elfix/pull/3 |
| |
| From 2a0dffbf0080dc74f82910a74f051d835cfd653f Mon Sep 17 00:00:00 2001 |
| From: Sam James <sam@gentoo.org> |
| Date: Fri, 6 Jan 2023 03:06:50 +0000 |
| Subject: [PATCH 1/2] install-xattr: avoid accessing empty storage |
| |
| UBSAN reports: |
| ``` |
| install-xattr.c:124:16: runtime error: load of address 0x55555556d440 with insufficient space for an object of type 'char' |
| 0x55555556d440: note: pointer points here |
| 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 61 00 00 00 |
| ^ |
| #0 0x555555557a27 in copyxattr /home/sam/git/elfix//install-xattr.c:124 |
| #1 0x555555556a4d in main /home/sam/git/elfix//install-xattr.c:410 |
| #2 0x7ffff77c864f (/usr/lib64/libc.so.6+0x2364f) |
| #3 0x7ffff77c8708 in __libc_start_main (/usr/lib64/libc.so.6+0x23708) |
| #4 0x555555557114 in _start (/home/sam/git/elfix//install-xattr+0x3114) |
| ``` |
| |
| Triggered with: |
| ``` |
| mkdir /tmp/a |
| touch /tmp/foo |
| ./install-xattr -c /tmp/foo /tmp/foo2 /tmp/a |
| ``` |
| |
| I don't see this with Clang or < GCC 12, but I do with GCC 13 (13.0.0_pre20230101 p5); |
| I suspect it's because of object-size improvements. |
| |
| Signed-off-by: Sam James <sam@gentoo.org> |
| --- a/install-xattr.c |
| +++ b/install-xattr.c |
| @@ -119,6 +119,10 @@ copyxattr(const char *source, const char *target) |
| lxattr = xmalloc(lsize); |
| xlistxattr(source, lxattr, lsize); |
| |
| + /* There's no xattrs at all. */ |
| + if (lsize == 0) |
| + return; |
| + |
| i = 0; |
| while (1) { |
| while (lxattr[i++] == 0) |
| -- |
| 2.39.0 |
