Dereferencing a null pointer on Clang is not a good idea - it will entirely optimise out the dereference. Make the pointer volatile to force the access (and fault).
Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202412140850.4TW4YBqc-lkp@intel.com/ Signed-off-by: Kevin Brodsky kevin.brodsky@arm.com ---
Hi Andrew,
Another fixup for an issue reported by the LKP CI (building with Clang instead of GCC). This should be squashed into the patch I'm replying to: "selftests/mm: Fix -Warray-bounds warnings in pkey_sighandler_tests"
Cheers, - Kevin
Cc: aruna.ramakrishna@oracle.com Cc: catalin.marinas@arm.com Cc: dave.hansen@linux.intel.com Cc: joey.gouly@arm.com Cc: keith.lucas@oracle.com Cc: ryan.roberts@arm.com Cc: shuah@kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kselftest@vger.kernel.org Cc: linux-mm@kvack.org Cc: x86@kernel.org --- tools/testing/selftests/mm/pkey_sighandler_tests.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c index 17bbfcd552c6..1ac8c8809880 100644 --- a/tools/testing/selftests/mm/pkey_sighandler_tests.c +++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c @@ -161,7 +161,7 @@ static void *thread_segv_with_pkey0_disabled(void *ptr) __write_pkey_reg(pkey_reg_restrictive_default());
/* Segfault (with SEGV_MAPERR) */ - *(int *)NULL = 1; + *(volatile int *)NULL = 1; return NULL; }
@@ -192,7 +192,7 @@ static void *thread_segv_maperr_ptr(void *ptr) __write_pkey_reg(pkey_reg);
/* Segfault */ - *(int *)NULL = 1; + *(volatile int *)NULL = 1; syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0); return NULL; }