author: Thomas Gleixner <tglx@linutronix.de> 2010-12-16 14:25:18 +0100
committer: Minda Chen <minda.chen@starfivetech.com> 2023-11-06 19:24:47 +0800
commit: d8902607cd38f270dd1ae41bfe301836970189d1
parent: 290e2dd97dee8962b42b20df60abc27a87ab7168
Commit Summary:
Diffstat:
1 file changed, 7 insertions, 1 deletion
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index 24a8d6c4fb18..2fc22c27df18 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -50,7 +50,7 @@
*/
static __always_inline void boot_init_stack_canary(void)
{
- u64 canary;
+ u64 canary = 0;
u64 tsc;
#ifdef CONFIG_X86_64
@@ -61,8 +61,14 @@ static __always_inline void boot_init_stack_canary(void)
* of randomness. The TSC only matters for very early init,
* there it already has some randomness on most systems. Later
* on during the bootup the random pool has true entropy too.
+ * For preempt-rt we need to weaken the randomness a bit, as
+ * we can't call into the random generator from atomic context
+ * due to locking constraints. We just leave canary
+ * uninitialized and use the TSC based randomness on top of it.
*/
+#ifndef CONFIG_PREEMPT_RT
get_random_bytes(&canary, sizeof(canary));
+#endif
tsc = rdtsc();
canary += tsc + (tsc << 32UL);
canary &= CANARY_MASK;