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Fix CVE-2017-5896:
https://bugs.ghostscript.com/show_bug.cgi?id=697515
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-5896
http://www.openwall.com/lists/oss-security/2017/02/10/1
https://security-tracker.debian.org/tracker/CVE-2017-5896
https://blogs.gentoo.org/ago/2017/02/09/mupdf-use-after-free-in-fz_subsample_pixmap-pixmap-c/
Patch lifted from upstream source repository:
http://git.ghostscript.com/?p=mupdf.git;h=2c4e5867ee699b1081527bc6c6ea0e99a35a5c27
From 2c4e5867ee699b1081527bc6c6ea0e99a35a5c27 Mon Sep 17 00:00:00 2001
From: Robin Watts <Robin.Watts@artifex.com>
Date: Thu, 9 Feb 2017 07:12:16 -0800
Subject: [PATCH] bug 697515: Fix out of bounds read in fz_subsample_pixmap
Pointer arithmetic for final special case was going wrong.
---
source/fitz/pixmap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/source/fitz/pixmap.c b/source/fitz/pixmap.c
index a8317127..f1291dc2 100644
--- a/source/fitz/pixmap.c
+++ b/source/fitz/pixmap.c
@@ -1104,6 +1104,7 @@ fz_subsample_pixmap_ARM(unsigned char *ptr, int w, int h, int f, int factor,
"@STACK:r1,<9>,factor,n,fwd,back,back2,fwd2,divX,back4,fwd4,fwd3,divY,back5,divXY\n"
"ldr r4, [r13,#4*22] @ r4 = divXY \n"
"ldr r5, [r13,#4*11] @ for (nn = n; nn > 0; n--) { \n"
+ "ldr r8, [r13,#4*17] @ r8 = back4 \n"
"18: @ \n"
"mov r14,#0 @ r14= v = 0 \n"
"sub r5, r5, r1, LSL #8 @ for (xx = x; xx > 0; x--) { \n"
@@ -1120,7 +1121,7 @@ fz_subsample_pixmap_ARM(unsigned char *ptr, int w, int h, int f, int factor,
"mul r14,r4, r14 @ r14= v *= divX \n"
"mov r14,r14,LSR #16 @ r14= v >>= 16 \n"
"strb r14,[r9], #1 @ *d++ = r14 \n"
- "sub r0, r0, r8 @ s -= back2 \n"
+ "sub r0, r0, r8 @ s -= back4 \n"
"subs r5, r5, #1 @ n-- \n"
"bgt 18b @ } \n"
"21: @ \n"
@@ -1249,6 +1250,7 @@ fz_subsample_pixmap(fz_context *ctx, fz_pixmap *tile, int factor)
x += f;
if (x > 0)
{
+ int back4 = x * n - 1;
div = x * y;
for (nn = n; nn > 0; nn--)
{
@@ -1263,7 +1265,7 @@ fz_subsample_pixmap(fz_context *ctx, fz_pixmap *tile, int factor)
s -= back5;
}
*d++ = v / div;
- s -= back2;
+ s -= back4;
}
}
}
--
2.12.0
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