[PATCH 17/22] panic: Disable SMAP in __stack_chk_fail()
From: Josh Poimboeuf
Date: Mon Mar 24 2025 - 18:00:09 EST
__stack_chk_fail() can be called from uaccess-enabled code. Make sure
uaccess gets disabled before calling panic().
Fixes the following warning:
kernel/trace/trace_branch.o: error: objtool: ftrace_likely_update+0x1ea: call to __stack_chk_fail() with UACCESS enabled
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
kernel/panic.c | 6 ++++++
tools/objtool/check.c | 5 ++++-
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/kernel/panic.c b/kernel/panic.c
index d8635d5cecb2..f9f0c5148f6a 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -832,9 +832,15 @@ device_initcall(register_warn_debugfs);
*/
__visible noinstr void __stack_chk_fail(void)
{
+ unsigned long flags;
+
instrumentation_begin();
+ flags = user_access_save();
+
panic("stack-protector: Kernel stack is corrupted in: %pB",
__builtin_return_address(0));
+
+ user_access_restore(flags);
instrumentation_end();
}
EXPORT_SYMBOL(__stack_chk_fail);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f4b9fcc395eb..a953ce5fe395 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1194,12 +1194,15 @@ static const char *uaccess_safe_builtin[] = {
"__ubsan_handle_load_invalid_value",
/* STACKLEAK */
"stackleak_track_stack",
+ /* TRACE_BRANCH_PROFILING */
+ "ftrace_likely_update",
+ /* STACKPROTECTOR */
+ "__stack_chk_fail",
/* misc */
"csum_partial_copy_generic",
"copy_mc_fragile",
"copy_mc_fragile_handle_tail",
"copy_mc_enhanced_fast_string",
- "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
"rep_stos_alternative",
"rep_movs_alternative",
"__copy_user_nocache",
--
2.48.1