From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
The kprobe_handler() code currently does not check if a pre_handler is
registered for the kprobe under process. This leads to a NULL pointer
dereference in cases when a module does not define a pre_handler.
The patch corrects the issue by explicitly checking that the pre_handler is
not NULL before it is invoked.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/i386/kernel/kprobes.c | 7 +++----
25-akpm/arch/ppc64/kernel/kprobes.c | 3 +--
25-akpm/arch/sparc64/kernel/kprobes.c | 2 +-
25-akpm/arch/x86_64/kernel/kprobes.c | 7 +++----
4 files changed, 8 insertions(+), 11 deletions(-)
diff -puN arch/i386/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function arch/i386/kernel/kprobes.c
--- 25/arch/i386/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function 2005-03-30 18:02:07.000000000 -0800
+++ 25-akpm/arch/i386/kernel/kprobes.c 2005-03-30 18:02:07.000000000 -0800
@@ -159,17 +159,16 @@ static int kprobe_handler(struct pt_regs
if (is_IF_modifier(p->opcode))
kprobe_saved_eflags &= ~IF_MASK;
- if (p->pre_handler(p, regs)) {
+ if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
return 1;
- }
- ss_probe:
+ss_probe:
prepare_singlestep(p, regs);
kprobe_status = KPROBE_HIT_SS;
return 1;
- no_kprobe:
+no_kprobe:
preempt_enable_no_resched();
return ret;
}
diff -puN arch/ppc64/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function arch/ppc64/kernel/kprobes.c
--- 25/arch/ppc64/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function 2005-03-30 18:02:07.000000000 -0800
+++ 25-akpm/arch/ppc64/kernel/kprobes.c 2005-03-30 18:02:07.000000000 -0800
@@ -128,10 +128,9 @@ static inline int kprobe_handler(struct
kprobe_status = KPROBE_HIT_ACTIVE;
current_kprobe = p;
kprobe_saved_msr = regs->msr;
- if (p->pre_handler(p, regs)) {
+ if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
return 1;
- }
ss_probe:
prepare_singlestep(p, regs);
diff -puN arch/sparc64/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function arch/sparc64/kernel/kprobes.c
--- 25/arch/sparc64/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function 2005-03-30 18:02:07.000000000 -0800
+++ 25-akpm/arch/sparc64/kernel/kprobes.c 2005-03-30 18:02:07.000000000 -0800
@@ -128,7 +128,7 @@ static int kprobe_handler(struct pt_regs
kprobe_status = KPROBE_HIT_ACTIVE;
current_kprobe = p;
- if (p->pre_handler(p, regs))
+ if (p->pre_handler && p->pre_handler(p, regs))
return 1;
ss_probe:
diff -puN arch/x86_64/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function arch/x86_64/kernel/kprobes.c
--- 25/arch/x86_64/kernel/kprobes.c~kprobe_handler-should-check-pre_handler-function 2005-03-30 18:02:07.000000000 -0800
+++ 25-akpm/arch/x86_64/kernel/kprobes.c 2005-03-30 18:02:07.000000000 -0800
@@ -293,17 +293,16 @@ int kprobe_handler(struct pt_regs *regs)
if (is_IF_modifier(p->ainsn.insn))
kprobe_saved_rflags &= ~IF_MASK;
- if (p->pre_handler(p, regs)) {
+ if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
return 1;
- }
- ss_probe:
+ss_probe:
prepare_singlestep(p, regs);
kprobe_status = KPROBE_HIT_SS;
return 1;
- no_kprobe:
+no_kprobe:
preempt_enable_no_resched();
return ret;
}
_