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SECURITY: disable build of filter_neon.S on arm

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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 <jbowler@acm.org>
This commit is contained in:
John Bowler 2024-05-30 07:53:42 -07:00
parent f1848a3b56
commit ceed2a3cf6
3 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
CMakeLists.txt
View File

@ -153,7 +153,7 @@ if(TARGET_ARCH MATCHES "^(ARM|arm|aarch)")
arm/arm_init.c arm/arm_init.c
arm/filter_neon_intrinsics.c arm/filter_neon_intrinsics.c
arm/palette_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) list(APPEND libpng_arm_sources arm/filter_neon.S)
endif() endif()
if(PNG_ARM_NEON STREQUAL "on") if(PNG_ARM_NEON STREQUAL "on")

6
Makefile.am
View File

@ -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 png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa
if PNG_ARM_NEON 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\ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
arm/filter_neon.S arm/filter_neon_intrinsics.c \ arm/filter_neon_intrinsics.c arm/palette_neon_intrinsics.c
arm/palette_neon_intrinsics.c
endif endif
if PNG_MIPS_MSA if PNG_MIPS_MSA

10
configure.ac
View File

@ -425,6 +425,16 @@ AM_CONDITIONAL([PNG_ARM_NEON],
*) test "$enable_arm_neon" != '' ;; *) test "$enable_arm_neon" != '' ;;
esac]) 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 # MIPS MSA
# ======== # ========