On Thu, Jan 06, 2022 at 03:19:59PM +0530, Naresh Kamboju wrote:

On Thu, 6 Jan 2022 at 15:02, Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:

...

On Thu, Jan 06, 2022 at 02:55:53PM +0530, Naresh Kamboju wrote:

...

While building selftests the following warnings were noticed for x86_64 architecture on Linux stable v5.15.13 kernel.

metadata: git repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git git commit: 734eb1fd2073f503f5c6b44f1c0d453ca6986b84 git describe: v5.15.13 toolchain": gcc-11 kernel-config: https://builds.tuxbuild.com/23HFo8abXIL6i4FFfSYiJlqAYMW/config

x86_64-linux-gnu-gcc -m64 -o \ /home/tuxbuild/.cache/tuxmake/builds/current/kselftest/x86/test_vsyscall_64 \ -O2 -g -std=gnu99 -pthread -Wall -no-pie \ -DCAN_BUILD_64 test_vsyscall.c helpers.h -lrt -ldl

test_vsyscall.c: In function 'test_process_vm_readv': test_vsyscall.c:500:22: warning: '__builtin_memcmp_eq' specified bound 4096 exceeds source size 0 [-Wstringop-overread] 500 | if (!memcmp(buf, (const void *)0xffffffffff600000, 4096)) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: Linux Kernel Functional Testing lkft@linaro.org

Build link: https://builds.tuxbuild.com/23HFo8abXIL6i4FFfSYiJlqAYMW/

# To install tuxmake on your system globally: # sudo pip3 install -U tuxmake

tuxmake --runtime podman --target-arch x86_64 --toolchain gcc-11 \ --kconfig https://builds.tuxbuild.com/23HFo8abXIL6i4FFfSYiJlqAYMW/config \ cpupower headers kernel kselftest kselftest-merge modules

Is this a new regression from 5.15.0? Is it also present on Linus's tree?

This build warning is not present in Linus's tree. Following patch to be backported to 5.15.x

---

...

From dd40f44eabe1e122c6852fabb298aac05b083fce Mon Sep 17 00:00:00 2001

From: Shuah Khan skhan@linuxfoundation.org Date: Thu, 21 Oct 2021 15:33:33 -0600 Subject: selftests: x86: fix [-Wstringop-overread] warn in test_process_vm_readv()

Fix the following [-Wstringop-overread] by passing in the variable instead of the value.

test_vsyscall.c: In function ‘test_process_vm_readv’: test_vsyscall.c:500:22: warning: ‘__builtin_memcmp_eq’ specified bound 4096 exceeds source size 0 [-Wstringop-overread] 500 | if (!memcmp(buf, (const void *)0xffffffffff600000, 4096)) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan skhan@linuxfoundation.org

Thanks, will go queue that up now.

greg k-h