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busybox: backport cve-2017-16544 fix

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In the add_match function in libbb/lineedit.c in BusyBox through 1.27.2,
the tab autocomplete feature of the shell, used to get a list of filenames
in a directory, does not sanitize filenames and results in executing any
escape sequence in the terminal. This could potentially result in code
execution, arbitrary file writes, or other attacks.

Fixes: FS#1181 - CVE-2017-16544:

Backport the patch from:
https://git.busybox.net/busybox/commit/?id=c3797d40a1c57352192c6106cc0f435e7d9c11e8
https://nvd.nist.gov/vuln/detail/CVE-2017-16544

Signed-off-by: Derek Werthmuller <thewerthfam@gmail.com>
Signed-off-by: John Crispin <john@phrozen.org>
This commit is contained in:
John Crispin 2018-01-01 11:46:03 +01:00
parent 0b1fa809d0
commit 7c0a2bc930
1 changed files with 40 additions and 0 deletions
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40
package/utils/busybox/patches/600-cve-2017-16544.patch Normal file
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@ -0,0 +1,40 @@
From c3797d40a1c57352192c6106cc0f435e7d9c11e8 Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Tue, 7 Nov 2017 18:09:29 +0100
Subject: lineedit: do not tab-complete any strings which have control
characters
function old new delta
add_match 41 68 +27
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
libbb/lineedit.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index c0e35bb..56e8140 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -645,6 +645,18 @@ static void free_tab_completion_data(void)
static void add_match(char *matched)
{
+ unsigned char *p = (unsigned char*)matched;
+ while (*p) {
+ /* ESC attack fix: drop any string with control chars */
+ if (*p < ' '
+ || (!ENABLE_UNICODE_SUPPORT && *p >= 0x7f)
+ || (ENABLE_UNICODE_SUPPORT && *p == 0x7f)
+ ) {
+ free(matched);
+ return;
+ }
+ p++;
+ }
matches = xrealloc_vector(matches, 4, num_matches);
matches[num_matches] = matched;
num_matches++;
--
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