[PATCH] i386: Disallow kprobes on NMI handlers
A kprobe executes IRET early and that could cause NMI recursion and stack
corruption.
Note: This problem was originally spotted and solved by Andi Kleen in the
x86_64 architecture. This patch is an adaption of his patch for i386.
AK: Merged with current code which was a bit different.
AK: Removed printk in nmi handler that shouldn't be there in the first time
AK: Added missing include.
AK: added KPROBES_END
Signed-off-by: Fernando Vazquez <fernando@intellilink.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index dede506..0928f70 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -729,7 +729,7 @@
* check whether we got an NMI on the debug path where the debug
* fault happened on the sysenter path.
*/
-ENTRY(nmi)
+KPROBE_ENTRY(nmi)
RING0_INT_FRAME
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
@@ -805,6 +805,7 @@
.align 4
.long 1b,iret_exc
.previous
+KPROBE_END(nmi)
KPROBE_ENTRY(int3)
RING0_INT_FRAME
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index 7b9a053..dbda706 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -22,6 +22,7 @@
#include <linux/sysctl.h>
#include <linux/percpu.h>
#include <linux/dmi.h>
+#include <linux/kprobes.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -882,7 +883,7 @@
extern void die_nmi(struct pt_regs *, const char *msg);
-int nmi_watchdog_tick (struct pt_regs * regs, unsigned reason)
+__kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
{
/*
@@ -962,8 +963,7 @@
* This matches the old behaviour.
*/
rc = 1;
- } else
- printk(KERN_WARNING "Unknown enabled NMI hardware?!\n");
+ }
}
done:
return rc;
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 00d643f..5c0f496 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -689,7 +689,8 @@
}
}
-static void mem_parity_error(unsigned char reason, struct pt_regs * regs)
+static __kprobes void
+mem_parity_error(unsigned char reason, struct pt_regs * regs)
{
printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x on "
"CPU %d.\n", reason, smp_processor_id());
@@ -704,7 +705,8 @@
clear_mem_error(reason);
}
-static void io_check_error(unsigned char reason, struct pt_regs * regs)
+static __kprobes void
+io_check_error(unsigned char reason, struct pt_regs * regs)
{
unsigned long i;
@@ -720,7 +722,8 @@
outb(reason, 0x61);
}
-static void unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
+static __kprobes void
+unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
{
#ifdef CONFIG_MCA
/* Might actually be able to figure out what the guilty party
@@ -741,7 +744,7 @@
static DEFINE_SPINLOCK(nmi_print_lock);
-void die_nmi (struct pt_regs *regs, const char *msg)
+void __kprobes die_nmi(struct pt_regs *regs, const char *msg)
{
if (notify_die(DIE_NMIWATCHDOG, msg, regs, 0, 2, SIGINT) ==
NOTIFY_STOP)
@@ -773,7 +776,7 @@
do_exit(SIGSEGV);
}
-static void default_do_nmi(struct pt_regs * regs)
+static __kprobes void default_do_nmi(struct pt_regs * regs)
{
unsigned char reason = 0;
@@ -811,7 +814,7 @@
reassert_nmi();
}
-fastcall void do_nmi(struct pt_regs * regs, long error_code)
+fastcall __kprobes void do_nmi(struct pt_regs * regs, long error_code)
{
int cpu;