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authorTejun Heo <tj@kernel.org>2009-02-11 16:31:00 +0900
committerIngo Molnar <mingo@elte.hu>2009-02-11 11:33:49 +0100
commit5c79d2a517a9905599d192db8ce77ab5f1a2faca (patch)
tree11f550a59b9b653fbd6c54b37effbf2d4a750fb5 /arch/x86/kernel/process_64.c
parent60a5317ff0f42dd313094b88f809f63041568b08 (diff)
x86: fix x86_32 stack protector bugs
Impact: fix x86_32 stack protector Brian Gerst found out that %gs was being initialized to stack_canary instead of stack_canary - 20, which basically gave the same canary value for all threads. Fixing this also exposed the following bugs. * cpu_idle() didn't call boot_init_stack_canary() * stack canary switching in switch_to() was being done too late making the initial run of a new thread use the old stack canary value. Fix all of them and while at it update comment in cpu_idle() about calling boot_init_stack_canary(). Reported-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r--arch/x86/kernel/process_64.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 8eb169e4558..836ef6575f0 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -120,12 +120,11 @@ void cpu_idle(void)
current_thread_info()->status |= TS_POLLING;
/*
- * If we're the non-boot CPU, nothing set the PDA stack
- * canary up for us - and if we are the boot CPU we have
- * a 0 stack canary. This is a good place for updating
- * it, as we wont ever return from this function (so the
- * invalid canaries already on the stack wont ever
- * trigger):
+ * If we're the non-boot CPU, nothing set the stack canary up
+ * for us. CPU0 already has it initialized but no harm in
+ * doing it again. This is a good place for updating it, as
+ * we wont ever return from this function (so the invalid
+ * canaries already on the stack wont ever trigger).
*/
boot_init_stack_canary();