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.
Signed-off-by: Fernando Vazquez <[email protected]>
---
diff -urNp linux-2.6.18-rc4-orig/arch/i386/kernel/entry.S linux-2.6.18-rc4/arch/i386/kernel/entry.S
--- linux-2.6.18-rc4-orig/arch/i386/kernel/entry.S 2006-08-10 20:04:10.000000000 +0900
+++ linux-2.6.18-rc4/arch/i386/kernel/entry.S 2006-08-10 20:06:11.000000000 +0900
@@ -725,7 +725,7 @@ debug_stack_correct:
* 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
diff -urNp linux-2.6.18-rc4-orig/arch/i386/kernel/nmi.c linux-2.6.18-rc4/arch/i386/kernel/nmi.c
--- linux-2.6.18-rc4-orig/arch/i386/kernel/nmi.c 2006-08-10 20:04:10.000000000 +0900
+++ linux-2.6.18-rc4/arch/i386/kernel/nmi.c 2006-08-10 20:07:06.000000000 +0900
@@ -21,6 +21,7 @@
#include <linux/sysdev.h>
#include <linux/sysctl.h>
#include <linux/percpu.h>
+#include <linux/kprobes.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -579,7 +580,7 @@ EXPORT_SYMBOL(touch_nmi_watchdog);
extern void die_nmi(struct pt_regs *, const char *msg);
-void nmi_watchdog_tick (struct pt_regs * regs)
+void __kprobes nmi_watchdog_tick (struct pt_regs * regs)
{
/*
diff -urNp linux-2.6.18-rc4-orig/arch/i386/kernel/traps.c linux-2.6.18-rc4/arch/i386/kernel/traps.c
--- linux-2.6.18-rc4-orig/arch/i386/kernel/traps.c 2006-08-10 20:04:11.000000000 +0900
+++ linux-2.6.18-rc4/arch/i386/kernel/traps.c 2006-08-10 20:06:11.000000000 +0900
@@ -626,7 +626,8 @@ gp_in_kernel:
}
}
-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. Dazed and confused, but trying "
"to continue\n");
@@ -637,7 +638,8 @@ static void mem_parity_error(unsigned ch
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;
@@ -653,7 +655,8 @@ static void io_check_error(unsigned char
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
@@ -671,7 +674,7 @@ static void unknown_nmi_error(unsigned c
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)
@@ -703,7 +706,7 @@ void die_nmi (struct pt_regs *regs, cons
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;
@@ -741,14 +744,14 @@ static void default_do_nmi(struct pt_reg
reassert_nmi();
}
-static int dummy_nmi_callback(struct pt_regs * regs, int cpu)
+static __kprobes int dummy_nmi_callback(struct pt_regs * regs, int cpu)
{
return 0;
}
static nmi_callback_t nmi_callback = dummy_nmi_callback;
-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;
-
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