* [PATCH] kprobes/x86: Check for invalid ftrace location in __recover_probed_insn()
@ 2015-02-03 16:21 Petr Mladek
2015-02-04 1:15 ` Masami Hiramatsu
0 siblings, 1 reply; 2+ messages in thread
From: Petr Mladek @ 2015-02-03 16:21 UTC (permalink / raw)
To: Masami Hiramatsu, David S. Miller, Anil S Keshavamurthy,
Ananth NMavinakayanahalli, Frederic Weisbecker
Cc: Steven Rostedt, Jiri Kosina, linux-kernel, Petr Mladek
__recover_probed_insn() should always be called from an address where
an instructions starts. The check for ftrace_location() might help to
discover a potential inconsistency. Something goes terribly wrong when
an address inside the ftrace location is checked. Let's BUG() in this case.
Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Petr Mladek <pmladek@suse.cz>
---
arch/x86/kernel/kprobes/core.c | 6 ++++++
1 file changed, 6 insertions(+)
This is follow up for the patch ("[PATCH v2] kprobes/x86: Use 5-byte NOP
when the code might be modified by ftrace") based on the Masami's
suggestion, see https://lkml.org/lkml/2015/2/3/207
Let me know if I should merge this with the first patch and send v3.
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 2f464b56766a..124577dcf768 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -228,6 +228,12 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
kp = get_kprobe((void *)addr);
faddr = ftrace_location(addr);
/*
+ * Addresses inside the ftrace location are refused by
+ * arch_check_ftrace_location(). Something went terribly wrong
+ * if such an address is checked here.
+ */
+ BUG_ON(faddr && faddr != addr);
+ /*
* Use the current code if it is not modified by Kprobe
* and it cannot be modified by ftrace.
*/
--
1.8.5.6
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] kprobes/x86: Check for invalid ftrace location in __recover_probed_insn()
2015-02-03 16:21 [PATCH] kprobes/x86: Check for invalid ftrace location in __recover_probed_insn() Petr Mladek
@ 2015-02-04 1:15 ` Masami Hiramatsu
0 siblings, 0 replies; 2+ messages in thread
From: Masami Hiramatsu @ 2015-02-04 1:15 UTC (permalink / raw)
To: Petr Mladek
Cc: David S. Miller, Anil S Keshavamurthy, Ananth NMavinakayanahalli,
Frederic Weisbecker, Steven Rostedt, Jiri Kosina, linux-kernel,
Ingo Molnar, Ingo Molnar
(2015/02/04 1:21), Petr Mladek wrote:
> __recover_probed_insn() should always be called from an address where
> an instructions starts. The check for ftrace_location() might help to
> discover a potential inconsistency. Something goes terribly wrong when
> an address inside the ftrace location is checked. Let's BUG() in this case.
Looks good to me :)
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thank you,
>
> Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Petr Mladek <pmladek@suse.cz>
> ---
> arch/x86/kernel/kprobes/core.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>
> This is follow up for the patch ("[PATCH v2] kprobes/x86: Use 5-byte NOP
> when the code might be modified by ftrace") based on the Masami's
> suggestion, see https://lkml.org/lkml/2015/2/3/207
>
> Let me know if I should merge this with the first patch and send v3.
>
>
> diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
> index 2f464b56766a..124577dcf768 100644
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -228,6 +228,12 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
> kp = get_kprobe((void *)addr);
> faddr = ftrace_location(addr);
> /*
> + * Addresses inside the ftrace location are refused by
> + * arch_check_ftrace_location(). Something went terribly wrong
> + * if such an address is checked here.
> + */
> + BUG_ON(faddr && faddr != addr);
> + /*
> * Use the current code if it is not modified by Kprobe
> * and it cannot be modified by ftrace.
> */
>
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
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