5.4-stable review patch. If anyone has any objections, please let me know.
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From: Neill Kapron nkapron@google.com
[ Upstream commit 797002deed03491215a352ace891749b39741b69 ]
The inconsistencies in the systcall ABI between arm and arm-compat can can cause a failure in the syscall_restart test due to the logic attempting to work around the differences. The 'machine' field for an ARM64 device running in compat mode can report 'armv8l' or 'armv8b' which matches with the string 'arm' when only examining the first three characters of the string.
This change adds additional validation to the workaround logic to make sure we only take the arm path when running natively, not in arm-compat.
Fixes: 256d0afb11d6 ("selftests/seccomp: build and pass on arm64") Signed-off-by: Neill Kapron nkapron@google.com Link: https://lore.kernel.org/r/20250427094103.3488304-2-nkapron@google.com Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/seccomp/seccomp_bpf.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 19c7351eeb74b..a12eea3aff104 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -2875,12 +2875,15 @@ TEST(syscall_restart) ret = get_syscall(_metadata, child_pid); #if defined(__arm__) /* - * FIXME: * - native ARM registers do NOT expose true syscall. * - compat ARM registers on ARM64 DO expose true syscall. + * - values of utsbuf.machine include 'armv8l' or 'armb8b' + * for ARM64 running in compat mode. */ ASSERT_EQ(0, uname(&utsbuf)); - if (strncmp(utsbuf.machine, "arm", 3) == 0) { + if ((strncmp(utsbuf.machine, "arm", 3) == 0) && + (strncmp(utsbuf.machine, "armv8l", 6) != 0) && + (strncmp(utsbuf.machine, "armv8b", 6) != 0)) { EXPECT_EQ(__NR_nanosleep, ret); } else #endif