| Message ID | 20230521-nolibc-automatic-stack-protector-v1-3-dad6c80c51c1@weissschuh.net (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | tools/nolibc: autodetect stackprotector availability from compiler | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/tree_selection | fail | Failed to apply to next/pending-fixes, riscv/for-next or riscv/master |
diff --git a/tools/include/nolibc/stackprotector.h b/tools/include/nolibc/stackprotector.h index 77e5251c4490..b0156fc077a0 100644 --- a/tools/include/nolibc/stackprotector.h +++ b/tools/include/nolibc/stackprotector.h @@ -45,8 +45,9 @@ __attribute__((weak,no_stack_protector,section(".text.nolibc_stack_chk"))) void __stack_chk_init(void) { my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0); - /* a bit more randomness in case getrandom() fails */ - __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard; + /* a bit more randomness in case getrandom() fails, ensure the guard is never 0 */ + if (__stack_chk_guard != (uintptr_t) &__stack_chk_guard) + __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard; } #endif /* defined(NOLIBC_STACKPROTECTOR) */
The all-zero pattern is one of the more probable out-of-bound writes so add a special case to not accidentally accept it. Also it enables the reliable detection of stack protector initialization during testing. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> --- tools/include/nolibc/stackprotector.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)