From c61d49d5cc592e07208fb6d85ba6e6edae455aff Mon Sep 17 00:00:00 2001
From: Matthew Jordan <mjordan@digium.com>
Date: Thu, 15 Mar 2012 18:55:54 +0000
Subject: [PATCH] Fix remotely exploitable stack overrun in Milliwatt
Milliwatt is vulnerable to a remotely exploitable stack overrun when using
the 'o' option. This occurs due to the milliwatt_generate function not
accounting for AST_FRIENDLY_OFFSET when calculating the maximum number of
samples it can put in the output buffer.
This patch resolves this issue by taking into account AST_FRIENDLY_OFFSET
when determining the maximum number of samples allowed. Note that at no
point is remote code execution possible. The data that is written into the
buffer is the pre-defined Milliwatt data, and not custom data.
(closes issue ASTERISK-19541)
Reported by: Russell Bryant
Tested by: Matt Jordan
Patches:
milliwatt_stack_overrun.rev1.txt by Russell Bryant (license 6283)
Note that this patch was written by Russell, even though Matt uploaded it
........
Merged revisions 359645 from http://svn.asterisk.org/svn/asterisk/branches/1.6.2
........
Merged revisions 359656 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 359694 from http://svn.asterisk.org/svn/asterisk/branches/10
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@359704 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
apps/app_milliwatt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/apps/app_milliwatt.c b/apps/app_milliwatt.c
index 4214141261..75d8037d61 100644
--- a/apps/app_milliwatt.c
+++ b/apps/app_milliwatt.c
@@ -78,7 +78,7 @@ static void milliwatt_release(struct ast_channel *chan, void *data)
static int milliwatt_generate(struct ast_channel *chan, void *data, int len, int samples)
{
unsigned char buf[AST_FRIENDLY_OFFSET + 640];
- const int maxsamples = ARRAY_LEN(buf);
+ const int maxsamples = ARRAY_LEN(buf) - (AST_FRIENDLY_OFFSET / sizeof(buf[0]));
int i, *indexp = (int *) data;
struct ast_frame wf = {
.frametype = AST_FRAME_VOICE,
--
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