From ceed2a3cf6af420a0782e7f6147d5965b01b772a Mon Sep 17 00:00:00 2001 From: John Bowler Date: Thu, 30 May 2024 07:53:42 -0700 Subject: [PATCH] SECURITY: disable build of filter_neon.S on arm This fixes the bug https://github.com/pnggroup/libpng/issues/505 "libpng does not support PAC/BTI on aarch64 targets" which arises because the build mechanisms (both cmake and configure) assemble arm/filter_neon.S even though it ends up completely empty. The empty file effectively poisons the so that the PAC/BTI support gets disabled. The fix is minimal; it simply removes arm/filter_neon.S from the list of sources included in the 64-bit ARM builds build. Note that this was already done in cmake for MSVC - it's not clear whether this change was a partial fix for the same issue. This version of the fix ONLY affects aarch64 (arm64) builds; 32-bit ARM systems can still invoke the assembler if required and, indeed, there should be no change whatsover to those builds. The assembler code could not be used on 64-bit systems in any case so in practice there is no material change to 64-bit builds either. TESTING: pull the changes then type "autoreconf" if using configure (not required for cmake). TESTS: cmake has not been tested because cross-builds with cmake currently fail to find the zlib installation from the cmake system root path. The following has been tested with configure cross builds: armv7-linux-gnueabi [no neon support] armv7a-linux-gnueabi [no neon support] armv7a-hardfloat-linux-gnueabi [neon support not enabled] armv7a-hardfloat-linux-gnueabi -mfpu=neon [uses intrinics] armv7a-hardfloat-linux-gnueabi -mfpu=neon -DPNG_ARM_NEON_IMPLEMENTATION=2 [uses assembler] aarch64-linux-gnu [uses intrinsics] aarch64-linux-gnu -DPNG_ARM_NEON_OPT=0 [neon support disabled] Signed-off-by: John Bowler --- CMakeLists.txt | 2 +- Makefile.am | 6 ++++-- configure.ac | 10 ++++++++++ 3 files changed, 15 insertions(+), 3 deletions(-) diff --git a/CMakeLists.txt b/CMakeLists.txt index 77e5398b6a..11bbe36d2a 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -153,7 +153,7 @@ if(TARGET_ARCH MATCHES "^(ARM|arm|aarch)") arm/arm_init.c arm/filter_neon_intrinsics.c arm/palette_neon_intrinsics.c) - if(NOT MSVC) + if(NOT MSVC AND NOT TARGET_ARCH MATCHES "^(ARM64|arm64|aarch64)") list(APPEND libpng_arm_sources arm/filter_neon.S) endif() if(PNG_ARM_NEON STREQUAL "on") diff --git a/Makefile.am b/Makefile.am index 1f06c703a1..5cc27a4c8f 100644 --- a/Makefile.am +++ b/Makefile.am @@ -107,9 +107,11 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\ png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa if PNG_ARM_NEON +if PNG_ARM_NEON_ASM +libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/filter_neon.S +endif libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\ - arm/filter_neon.S arm/filter_neon_intrinsics.c \ - arm/palette_neon_intrinsics.c + arm/filter_neon_intrinsics.c arm/palette_neon_intrinsics.c endif if PNG_MIPS_MSA diff --git a/configure.ac b/configure.ac index 2c6b3333c6..e3c1536f0c 100644 --- a/configure.ac +++ b/configure.ac @@ -425,6 +425,16 @@ AM_CONDITIONAL([PNG_ARM_NEON], *) test "$enable_arm_neon" != '' ;; esac]) +# Add the assembler implementation source file. This only works on 32-bit +# ARM and causes problems even if empty on 64-bit ARM. +AM_CONDITIONAL([PNG_ARM_NEON_ASM], + [test "$enable_arm_neon" != 'no' && + case "$host_cpu" in + arm64*|aarch64*) false ;; + arm*) true ;; + *) test "$enable_arm_neon" != '' ;; + esac]) + # MIPS MSA # ========