| CVE: CVE-2018-1000879 |
| Upstream-Status: Backport |
| Signed-off-by: Ross Burton <ross.burton@intel.com> |
| |
| From 15bf44fd2c1ad0e3fd87048b3fcc90c4dcff1175 Mon Sep 17 00:00:00 2001 |
| From: Daniel Axtens <dja@axtens.net> |
| Date: Tue, 4 Dec 2018 14:29:42 +1100 |
| Subject: [PATCH] Skip 0-length ACL fields |
| |
| Currently, it is possible to create an archive that crashes bsdtar |
| with a malformed ACL: |
| |
| Program received signal SIGSEGV, Segmentation fault. |
| archive_acl_from_text_l (acl=<optimised out>, text=0x7e2e92 "", want_type=<optimised out>, sc=<optimised out>) at libarchive/archive_acl.c:1726 |
| 1726 switch (*s) { |
| (gdb) p n |
| $1 = 1 |
| (gdb) p field[n] |
| $2 = {start = 0x0, end = 0x0} |
| |
| Stop this by checking that the length is not zero before beginning |
| the switch statement. |
| |
| I am pretty sure this is the bug mentioned in the qsym paper [1], |
| and I was able to replicate it with a qsym + AFL + afl-rb setup. |
| |
| [1] https://www.usenix.org/conference/usenixsecurity18/presentation/yun |
| --- |
| libarchive/archive_acl.c | 5 +++++ |
| 1 file changed, 5 insertions(+) |
| |
| diff --git a/libarchive/archive_acl.c b/libarchive/archive_acl.c |
| index 512beee1..7beeee86 100644 |
| --- a/libarchive/archive_acl.c |
| +++ b/libarchive/archive_acl.c |
| @@ -1723,6 +1723,11 @@ archive_acl_from_text_l(struct archive_acl *acl, const char *text, |
| st = field[n].start + 1; |
| len = field[n].end - field[n].start; |
| |
| + if (len == 0) { |
| + ret = ARCHIVE_WARN; |
| + continue; |
| + } |
| + |
| switch (*s) { |
| case 'u': |
| if (len == 1 || (len == 4 |
| -- |
| 2.20.0 |
| |