XPost: linux.debian.ports.sparc
From: glaubitz@physik.fu-berlin.de
This is a multi-part MIME message sent by reportbug.
Source: zopfli
Version: 1.0.3-3
Severity: important
User: debian-sparc@lists.debian.org
Usertags: sparc64
X-Debbugs-Cc: debian-sparc@lists.debian.org
Hi,
there are some instances of unaligned access in zopfli that trigger Bus error
crashes on sparc64 when running the testsuite of python-zopfli on sparc64 [1].
The upstream of python-zopfli just fixed [2] the issue after I reported it [3].
I'm attaching the patch, please considers cherry-picking it.
Thanks,
Adrian
> [1] https://buildd.debian.org/status/fetch.php?pkg=python-zopf
i&arch=sparc64&ver=0.4.0-1&stamp=1762664749&raw=0
> [2] https://github.com/fonttools/py-zopfli/commit/f87d464d1df5
07d0035f559278421b125236fc5
> [3] https://github.com/fonttools/py-zopfli/issues/28
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
From cd7f13b12a2c1a50f94ffe9ca5909854bdef8d93 Mon Sep 17 00:00:00 2001
From: Cosimo Lupo
Date: Fri, 13 Feb 2026 11:57:17 +0000
Subject: [PATCH] Fix SIGBUS on strict-alignment architectures (SPARC, MIPS)
GetMatch() casts unsigned char* pointers to size_t* and unsigned int*
and dereferences them for word-at-a-time comparison. These pointers
can be at any byte offset, so the casts produce unaligned accesses
which cause SIGBUS on strict-alignment architectures (SPARC, MIPS64,
etc.) and are undefined behavior per the C standard.
Replace the direct pointer casts with memcpy into properly aligned
local variables. Modern compilers optimize memcpy of a known small
size into a single load instruction on architectures that support
unaligned access (x86), so there is no performance regression.
Fixes google/zopfli#22 (open since 2013).
Also fixes fonttools/py-zopfli#28.
---
src/zopfli/lz77.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/src/zopfli/lz77.c b/src/zopfli/lz77.c
index 9df899dd..52a2bed1 100644
--- a/src/zopfli/lz77.c
+++ b/src/zopfli/lz77.c
@@ -24,6 +24,7 @@ Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala)
#include
#include
#include
+#include
void ZopfliInitLZ77Store(const unsigned char* data, ZopfliLZ77Store* store) {
store->size = 0;
@@ -300,15 +301,25 @@ static const unsigned char* GetMatch(const unsigned
char* scan,
const unsigned char* safe_end) {
if (sizeof(size_t) == 8) {
- /* 8 checks at once per array bounds check (size_t is 64-bit). */
- while (scan < safe_end && *((size_t*)scan) == *((size_t*)match)) {
+ /* 8 checks at once per array bounds check (size_t is 64-bit).
+ Use memcpy to avoid unaligned access (causes SIGBUS on strict-alignment
+ architectures like SPARC and MIPS). The compiler will optimize memcpy
of
+ a known size into a single load where the architecture supports it. */
+ size_t sv, mv;
+ while (scan < safe_end) {
+ memcpy(&sv, scan, sizeof(sv));
+ memcpy(&mv, match, sizeof(mv));
+ if (sv != mv) break;
scan += 8;
match += 8;
}
} else if (sizeof(unsigned int) == 4) {
/* 4 checks at once per array bounds check (unsigned int is 32-bit). */
- while (scan < safe_end
- && *((unsigned int*)scan) == *((unsigned int*)match)) {
+ unsigned int sv, mv;
+ while (scan < safe_end) {
+ memcpy(&sv, scan, sizeof(sv));
+ memcpy(&mv, match, sizeof(mv));
+ if (sv != mv) break;
scan += 4;
match += 4;
}
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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