| Age | Commit message (Collapse) | Author |
|---|
|
clang recently added support for -Wstringop-overread [1], which is on by
default like -Wfortify-source. This breaks the usage of -Werror in the
fortify tests, resulting in the following false positive warnings in the
kernel build:
warning: unsafe memcmp() usage lacked '__read_overflow2' warning in lib/test_fortify/read_overflow2-memcmp.c
warning: unsafe memcmp() usage lacked '__read_overflow' warning in lib/test_fortify/read_overflow-memcmp.c
warning: unsafe memchr() usage lacked '__read_overflow' warning in lib/test_fortify/read_overflow-memchr.c
Examining the fortify test logs shows a warning like the following in
each of the failed logs:
In file included from lib/test_fortify/read_overflow2-memcmp.c:5:
lib/test_fortify/test_fortify.h:34:2: error: 'memcmp' reading 17 bytes from a region of size 16 [-Werror,-Wstringop-overread]
34 | TEST;
| ^
lib/test_fortify/read_overflow2-memcmp.c:3:2: note: expanded from macro 'TEST'
3 | memcmp(large, small, sizeof(small) + 1)
| ^
1 error generated.
Disable -Wstringop-overread for the fortify tests, as it defeats the
purpose of testing the Linux specific implementation of fortify, like
-Wfortify-source.
Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/2168
Link: https://github.com/llvm/llvm-project/commit/86f2e71cb8d165b59ad31a442b2391e23826133e [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260623-fix-test_fortify-for-clang-stringop-overread-v1-1-15ee8342a953@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
|
|
Commit a3e8fe814ad1 ("x86/build: Raise the minimum GCC version to 8.1")
raised the minimum compiler version as enforced by Kbuild to gcc-8.1
and clang-15 for x86.
This is actually the same gcc version that has been discussed as the
minimum for all architectures several times in the past, with little
objection. A previous concern was the kernel for SLE15-SP7 needing to
be built with gcc-7. As this ended up still using linux-6.4 and there
is no plan for an SP8, this is no longer a problem.
Change it for all architectures and adjust the documentation accordingly.
A few version checks can be removed in the process. The binutils
version 2.30 is the lowest version used in combination with gcc-8 on
common distros, so use that as the corresponding minimum.
Link: https://lore.kernel.org/lkml/20240925150059.3955569-32-ardb+git@google.com/
Link: https://lore.kernel.org/lkml/871q7yxrgv.wl-tiwai@suse.de/
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
|
|
After building with CONFIG_FORTIFY_SOURCE=y, many .*.d files are left
in lib/test_fortify/ because the compiler outputs header dependencies
into *.d without fixdep being invoked.
When compiling C files, if_changed_dep should be used so that the
auto-generated header dependencies are recorded in .*.cmd files.
Currently, if_changed is incorrectly used, and only two headers are
hard-coded in lib/Makefile.
In the previous patch version, the kbuild test robot detected new errors
on GCC 7.
GCC 7 or older does not produce test.d with the following test code:
$ echo 'void b(void) __attribute__((__error__(""))); void a(void) { b(); }' |
gcc -Wp,-MMD,test.d -c -o /dev/null -x c -
Perhaps, this was a bug that existed in older GCC versions.
Skip the tests for GCC<=7 for now, as this will be eventually solved
when we bump the minimal supported GCC version.
Link: https://lore.kernel.org/oe-kbuild-all/CAK7LNARmJcyyzL-jVJfBPi3W684LTDmuhMf1koF0TXoCpKTmcw@mail.gmail.com/T/#m13771bf78ae21adff22efc4d310c973fb4bcaf67
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240727150302.1823750-4-masahiroy@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
|
|
This script is only used in lib/test_fortify/.
There is no reason to keep it in scripts/.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240727150302.1823750-3-masahiroy@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
|
|
There are some issues in the test_fortify Makefile code.
Problem 1: cc-disable-warning invokes compiler dozens of times
To see how many times the cc-disable-warning is evaluated, change
this code:
$(call cc-disable-warning,fortify-source)
to:
$(call cc-disable-warning,$(shell touch /tmp/fortify-$$$$)fortify-source)
Then, build the kernel with CONFIG_FORTIFY_SOURCE=y. You will see a
large number of '/tmp/fortify-<PID>' files created:
$ ls -1 /tmp/fortify-* | wc
80 80 1600
This means the compiler was invoked 80 times just for checking the
-Wno-fortify-source flag support.
$(call cc-disable-warning,fortify-source) should be added to a simple
variable instead of a recursive variable.
Problem 2: do not recompile string.o when the test code is updated
The test cases are independent of the kernel. However, when the test
code is updated, $(obj)/string.o is rebuilt and vmlinux is relinked
due to this dependency:
$(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG)
always-y is suitable for building the log files.
Problem 3: redundant code
clean-files += $(addsuffix .o, $(TEST_FORTIFY_LOGS))
... is unneeded because the top Makefile globally cleans *.o files.
This commit fixes these issues and makes the code readable.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240727150302.1823750-2-masahiroy@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
|
