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kprobes/x86: Don't try to resolve kprobe faults from userspace

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This commit:

    commit 6f6343f53d
    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>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/c4e339882c121aa76254f2adde3fcbdf502faec2.1405099506.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2014-07-11 10:27:01 -07:00 committed by Ingo Molnar
parent 4485154138
commit 0cdd192cf4
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kernel/kprobes/core.c
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@ -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