selftests/fchmodat2: fix clang build failure due to -static-libasan

gcc requires -static-libasan in order to ensure that Address Sanitizer's
library is the first one loaded. However, this leads to b

selftests/fchmodat2: fix clang build failure due to -static-libasan

gcc requires -static-libasan in order to ensure that Address Sanitizer's
library is the first one loaded. However, this leads to build failures
on clang, when building via:

make LLVM=1 -C tools/testing/selftests

However, clang already does the right thing by default: it statically
links the Address Sanitizer if -fsanitize is specified. Therefore,
simply omit -static-libasan for clang builds. And leave behind a
comment, because the whole reason for static linking might not be
obvious.

Cc: Ryan Roberts <[email protected]>
Signed-off-by: John Hubbard <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

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selftests: link libasan statically for tests with -fsanitize=address

When dynamically linking, Address Sanitizer requires its library to be the
first one to be loaded; this is apparently to ensure t

selftests: link libasan statically for tests with -fsanitize=address

When dynamically linking, Address Sanitizer requires its library to be the
first one to be loaded; this is apparently to ensure that every call to
malloc is intercepted. If using LD_PRELOAD, those listed libraries will
be loaded before the libraries listed in the program's ELF and will
therefore violate this requirement, leading to the below failure and
output from ASan.

commit 58e2847ad2e6 ("selftests: line buffer test program's stdout")
modified the kselftest runner to force line buffering by forcing the test
programs to run through `stdbuf`. It turns out that stdbuf implements
line buffering by injecting a library via LD_PRELOAD. Therefore selftests
that use ASan started failing.

Fix this by statically linking libasan in the affected test programs,
using the `-static-libasan` option. Note this is already the default for
Clang, but not got GCC.

Test output sample for failing case:

TAP version 13
1..3
# timeout set to 300
# selftests: openat2: openat2_test
# ==4052==ASan runtime does not come first in initial library list;
you should either link runtime to your application or manually preload
it with LD_PRELOAD.
not ok 1 selftests: openat2: openat2_test # exit=1
# timeout set to 300
# selftests: openat2: resolve_test
# ==4070==ASan runtime does not come first in initial library list;
you should either link runtime to your application or manually preload
it with LD_PRELOAD.
not ok 2 selftests: openat2: resolve_test # exit=1

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ryan Roberts <[email protected]>
Fixes: 58e2847ad2e6 ("selftests: line buffer test program's stdout")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Cc: David Hildenbrand <[email protected]>
Cc: Florent Revest <[email protected]>
Cc: Jérôme Glisse <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Tom Rix <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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selftests: fchmodat2: remove duplicate unneeded defines

These duplicate defines should automatically be picked up from kernel
headers. Use KHDR_INCLUDES to add kernel header files.

Signed-off-by: M

selftests: fchmodat2: remove duplicate unneeded defines

These duplicate defines should automatically be picked up from kernel
headers. Use KHDR_INCLUDES to add kernel header files.

Signed-off-by: Muhammad Usama Anjum <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

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selftests: Add fchmodat2 selftest

The test marks as skipped if a syscall with the AT_SYMLINK_NOFOLLOW flag
fails. This is because not all filesystems support changing the mode
bits of symlinks prope

selftests: Add fchmodat2 selftest

The test marks as skipped if a syscall with the AT_SYMLINK_NOFOLLOW flag
fails. This is because not all filesystems support changing the mode
bits of symlinks properly. These filesystems return an error but change
the mode bits:

newfstatat(4, "regfile", {st_mode=S_IFREG|0640, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
newfstatat(4, "symlink", {st_mode=S_IFLNK|0777, st_size=7, ...}, AT_SYMLINK_NOFOLLOW) = 0
syscall_0x1c3(0x4, 0x55fa1f244396, 0x180, 0x100, 0x55fa1f24438e, 0x34) = -1 EOPNOTSUPP (Operation not supported)
newfstatat(4, "regfile", {st_mode=S_IFREG|0640, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0

This happens with btrfs and xfs:

$ tools/testing/selftests/fchmodat2/fchmodat2_test
TAP version 13
1..1
ok 1 # SKIP fchmodat2(symlink)
# Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0

$ stat /tmp/ksft-fchmodat2.*/symlink
File: /tmp/ksft-fchmodat2.3NCqlE/symlink -> regfile
Size: 7 Blocks: 0 IO Block: 4096 symbolic link
Device: 7,0 Inode: 133 Links: 1
Access: (0600/lrw-------) Uid: ( 0/ root) Gid: ( 0/ root)

Signed-off-by: Alexey Gladkov <[email protected]>
Message-Id: <4532a04a870ff589ba62ceeacf76f0bd81b9ba01.1689092120.git.legion@kernel.org>
Signed-off-by: Christian Brauner <[email protected]>

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