lkml.org 
[lkml]   [2023]   [Feb]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/3] x86/kprobes: Fix __recover_optprobed_insn check optimizing logic
From
Date
Hello Masami,

On 2023/2/15 23:08, Masami Hiramatsu (Google) wrote:
> On Wed, 15 Feb 2023 19:54:29 +0800
> Yang Jihong <yangjihong1@huawei.com> wrote:
>
>> Since the following commit:
>>
>> commit f66c0447cca1 ("kprobes: Set unoptimized flag after unoptimizing code")
>>
>> modified the update timing of the KPROBE_FLAG_OPTIMIZED, a optimized_kprobe
>> may be in the optimizing or unoptimizing state when op.kp->flags
>> has KPROBE_FLAG_OPTIMIZED and op->list is not empty.
>>
>> The __recover_optprobed_insn check logic is incorrect, a kprobe in the
>> unoptimizing state may be incorrectly determined as unoptimizing.
>> As a result, incorrect instructions are copied.
>
> Ah, good catch!
>
>>
>> The optprobe_queued_unopt function needs to be exported for invoking in
>> arch directory.
>>
>> Fixes: f66c0447cca1 ("kprobes: Set unoptimized flag after unoptimizing code")
>
> Cc: stable@vger.kernel.org

OK, will add in next version.

>
>> Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
>> ---
>> arch/x86/kernel/kprobes/opt.c | 4 ++--
>> include/linux/kprobes.h | 1 +
>> kernel/kprobes.c | 2 +-
>> 3 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
>> index e57e07b0edb6..3718d6863555 100644
>> --- a/arch/x86/kernel/kprobes/opt.c
>> +++ b/arch/x86/kernel/kprobes/opt.c
>> @@ -46,8 +46,8 @@ unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
>> /* This function only handles jump-optimized kprobe */
>> if (kp && kprobe_optimized(kp)) {
>> op = container_of(kp, struct optimized_kprobe, kp);
>> - /* If op->list is not empty, op is under optimizing */
>> - if (list_empty(&op->list))
>> + /* If op is [un]optimized or under unoptimizing */
>
> Hmm, this is a bit confusing comment. If it is unoptimized, the kprobe_optimized() returns false.
> Thus the comment should be /* If op is optimized or under unoptimizing */.
>

OK, will fix in next version.

Thanks,
Yang.

\
 
 \ /
  Last update: 2023-03-27 00:25    [W:0.045 / U:0.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site