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liblzma: Add overflow check for Unpadded size in lzma_index_append

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kouwenqi 2024-04-30 11:03:07 +08:00
parent deb5a86780
commit 5275a6fd07
2 changed files with 65 additions and 1 deletions
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backport-liblzma-Add-overflow-check-for-Unpadded-size-in-lzma.patch Normal file
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@ -0,0 +1,60 @@
From 68bda971bb8b666a009331455fcedb4e18d837a4 Mon Sep 17 00:00:00 2001
From: Jia Tan <jiat0218@gmail.com>
Date: Mon, 28 Aug 2023 21:31:25 +0800
Subject: [PATCH] liblzma: Add overflow check for Unpadded size in
lzma_index_append().
This was not a security bug since there was no path to overflow
UINT64_MAX in lzma_index_append() or when it calls index_file_size().
The bug was discovered by a failing assert() in vli_ceil4() when called
from index_file_size() when unpadded_sum (the sum of the compressed size
of current Stream and the unpadded_size parameter) exceeds LZMA_VLI_MAX.
Previously, the unpadded_size parameter was checked to be not greater
than UNPADDED_SIZE_MAX, but no check was done once compressed_base was
added.
This could not have caused an integer overflow in index_file_size() when
called by lzma_index_append(). The calculation for file_size breaks down
into the sum of:
- Compressed base from all previous Streams
- 2 * LZMA_STREAM_HEADER_SIZE (size of the current Streams header and
footer)
- stream_padding (can be set by lzma_index_stream_padding())
- Compressed base from the current Stream
- Unpadded size (parameter to lzma_index_append())
The sum of everything except for Unpadded size must be less than
LZMA_VLI_MAX. This is guarenteed by overflow checks in the functions
that can set these values including lzma_index_stream_padding(),
lzma_index_append(), and lzma_index_cat(). The maximum value for
Unpadded size is enforced by lzma_index_append() to be less than or
equal UNPADDED_SIZE_MAX. Thus, the sum cannot exceed UINT64_MAX since
LZMA_VLI_MAX is half of UINT64_MAX.
Thanks to Joona Kannisto for reporting this.
---
src/liblzma/common/index.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/src/liblzma/common/index.c b/src/liblzma/common/index.c
index 97cc9f95..8a35f439 100644
--- a/src/liblzma/common/index.c
+++ b/src/liblzma/common/index.c
@@ -661,6 +661,12 @@ lzma_index_append(lzma_index *i, const lzma_allocator *allocator,
if (uncompressed_base + uncompressed_size > LZMA_VLI_MAX)
return LZMA_DATA_ERROR;
+ // Check that the new unpadded sum will not overflow. This is
+ // checked again in index_file_size(), but the unpadded sum is
+ // passed to vli_ceil4() which expects a valid lzma_vli value.
+ if (compressed_base + unpadded_size > UNPADDED_SIZE_MAX)
+ return LZMA_DATA_ERROR;
+
// Check that the file size will stay within limits.
if (index_file_size(s->node.compressed_base,
compressed_base + unpadded_size, s->record_count + 1,
--
2.23.0

6
xz.spec
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@ -1,12 +1,13 @@
Name: xz
Version: 5.4.4
Release: 1
Release: 2
Summary: A free general-purpose data compreession software with LZMA2 algorithm
License: GPL-3.0-only
URL: http://tukaani.org/xz
Source0: http://tukaani.org/%{name}/%{name}-%{version}.tar.xz
Source1: colorxzgrep.sh
Source2: colorxzgrep.csh
Patch0: backport-liblzma-Add-overflow-check-for-Unpadded-size-in-lzma.patch
BuildRequires: perl-interpreter gcc
@ -114,6 +115,9 @@ LD_LIBRARY_PATH=$PWD/src/liblzma/.libs make check
%{_mandir}/pt_BR/man1/*
%changelog
* Tue Apr 30 2024 kouwenqi <kouwenqi@kylinos.cn> - 5.4.4-2
- liblzma: Add overflow check for Unpadded size in lzma_index_append
* Fri Aug 4 2023 dillon chen <dillon.chen@gmail.com> - 5.4.4-1
- update version to 5.4.4