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- 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 512beee1f..7beeee86e 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
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