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Subject[PATCH v2 3.16] x86,kprobes: Don't try to resolve kprobe faults from userspace
Date
This commit:

commit 6f6343f53d133bae516caf3d254bce37d8774625
Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Date: Thu Apr 17 17:17:33 2014 +0900

kprobes/x86: Call exception handlers directly from do_int3/do_debug

appears to have inadvertently dropped a check that the int3 came
from kernel mode. Trying to dereference addr when addr is
user-controlled is completely bogus.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---

Changes from v1: Fixed the changelog message

arch/x86/kernel/kprobes/core.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 7596df6..67e6d19 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -574,6 +574,9 @@ int kprobe_int3_handler(struct pt_regs *regs)
struct kprobe *p;
struct kprobe_ctlblk *kcb;

+ if (user_mode_vm(regs))
+ return 0;
+
addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
/*
* We don't want to be preempted for the entire
--
1.9.3


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