This patch fixes a bug of jprobe and cleans up. jprobe for x86-64
can cause kernel page fault when the jprobe_return() is called from
incorrect function. Anyway, that path finally invokes BUG() macro,
so this is not so serious.

Based on patch from Masami Hiramatsu

- Use jprobe_saved_regs instead getting it from stack.
(Especially on x86-64, it may get incorrect data, because
pt_regs can not be get by using container_of(rsp))
- Change the type of stack pointer to unsigned long *.

Signed-off-by: Harvey Harrison
---
arch/x86/kernel/kprobes.c | 8 ++------
include/asm-x86/kprobes.h | 2 +-
2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index e5b7d07..9130c01 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -1022,16 +1022,12 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
#ifdef CONFIG_X86_32
if (&regs->sp != kcb->jprobe_saved_sp) {
- struct pt_regs *saved_regs =
- container_of(kcb->jprobe_saved_sp,
- struct pt_regs, sp);
+ struct pt_regs *saved_regs = &kcb->jprobe_saved_sp;
printk("current sp %p does not match saved sp %p\n",
&regs->sp, kcb->jprobe_saved_sp);
#else
if ((long *)regs->sp != kcb->jprobe_saved_sp) {
- struct pt_regs *saved_regs =
- container_of(kcb->jprobe_saved_sp,
- struct pt_regs, sp);
+ struct pt_regs *saved_regs = &kcb->jprobe_saved_sp;
printk("current sp %p does not match saved sp %p\n",
(long *)regs->sp, kcb->jprobe_saved_sp);
#endif
diff --git a/include/asm-x86/kprobes.h b/include/asm-x86/kprobes.h
index e348ed6..7319c62 100644
--- a/include/asm-x86/kprobes.h
+++ b/include/asm-x86/kprobes.h
@@ -79,7 +79,7 @@ struct kprobe_ctlblk {
unsigned long kprobe_status;
unsigned long kprobe_old_flags;
unsigned long kprobe_saved_flags;
- long *jprobe_saved_sp;
+ unsigned long *jprobe_saved_sp;
struct pt_regs jprobe_saved_regs;
kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
struct prev_kprobe prev_kprobe;
--
1.5.4.rc0.1083.gf568


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