* [PATCH] time: Validate the usec before covert to nsec in do_adjtimex
@ 2019-07-08 7:55 ZhangXiaoxu
2019-07-08 9:24 ` Thomas Gleixner
2019-07-08 16:39 ` Richard Cochran
0 siblings, 2 replies; 4+ messages in thread
From: ZhangXiaoxu @ 2019-07-08 7:55 UTC (permalink / raw)
To: john.stultz, tglx, sboyd, zhangxiaoxu5, linux-kernel
When covert the usec to nsec, it will multiple 1000, it maybe
overflow and lead an undefined behavior.
For example, users may input an negative tv_usec values when
call adjtimex syscall, then multiple 1000 maybe overflow it
to a positive and legal number.
So, we should validate the usec before coverted it to nsec.
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
---
kernel/time/timekeeping.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 44b726b..e5c1d00 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1272,9 +1272,6 @@ static int timekeeping_inject_offset(const struct timespec64 *ts)
struct timespec64 tmp;
int ret = 0;
- if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
- return -EINVAL;
-
raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&tk_core.seq);
@@ -2321,6 +2318,9 @@ int do_adjtimex(struct __kernel_timex *txc)
if (txc->modes & ADJ_SETOFFSET) {
struct timespec64 delta;
+
+ if (txc->time.tv_usec < 0 || txc->time.tv_usec >= USEC_PER_SEC)
+ return -EINVAL;
delta.tv_sec = txc->time.tv_sec;
delta.tv_nsec = txc->time.tv_usec;
if (!(txc->modes & ADJ_NANO))
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] time: Validate the usec before covert to nsec in do_adjtimex
2019-07-08 7:55 [PATCH] time: Validate the usec before covert to nsec in do_adjtimex ZhangXiaoxu
@ 2019-07-08 9:24 ` Thomas Gleixner
2019-07-08 10:42 ` zhangxiaoxu (A)
2019-07-08 16:39 ` Richard Cochran
1 sibling, 1 reply; 4+ messages in thread
From: Thomas Gleixner @ 2019-07-08 9:24 UTC (permalink / raw)
To: ZhangXiaoxu; +Cc: john.stultz, sboyd, linux-kernel
On Mon, 8 Jul 2019, ZhangXiaoxu wrote:
> When covert the usec to nsec, it will multiple 1000, it maybe
> overflow and lead an undefined behavior.
>
> For example, users may input an negative tv_usec values when
> call adjtimex syscall, then multiple 1000 maybe overflow it
> to a positive and legal number.
>
> So, we should validate the usec before coverted it to nsec.
That's correct, but the actuall inject function wants to keep the sanity
check,
Thanks,
tglx
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] time: Validate the usec before covert to nsec in do_adjtimex
2019-07-08 9:24 ` Thomas Gleixner
@ 2019-07-08 10:42 ` zhangxiaoxu (A)
0 siblings, 0 replies; 4+ messages in thread
From: zhangxiaoxu (A) @ 2019-07-08 10:42 UTC (permalink / raw)
To: Thomas Gleixner; +Cc: john.stultz, sboyd, linux-kernel
在 2019/7/8 17:24, Thomas Gleixner 写道:
> On Mon, 8 Jul 2019, ZhangXiaoxu wrote:
>
>> When covert the usec to nsec, it will multiple 1000, it maybe
>> overflow and lead an undefined behavior.
>>
>> For example, users may input an negative tv_usec values when
>> call adjtimex syscall, then multiple 1000 maybe overflow it
>> to a positive and legal number.
>>
>> So, we should validate the usec before coverted it to nsec.
>
> That's correct, but the actuall inject function wants to keep the sanity
> check,
timekeeping_inject_offset is called only by timekeeping_warp_clock and do_adjtimex.
The do_adjtimex already validate it, and timekeeping_warp_clock is set tv_nsec=0.
We keep the sanity check is for some other maybe use this function?
I had send a v2 to keep the sanity check in timekeeping_inject_offset.
Thanks.
>
> Thanks,
>
> tglx
>
> .
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] time: Validate the usec before covert to nsec in do_adjtimex
2019-07-08 7:55 [PATCH] time: Validate the usec before covert to nsec in do_adjtimex ZhangXiaoxu
2019-07-08 9:24 ` Thomas Gleixner
@ 2019-07-08 16:39 ` Richard Cochran
1 sibling, 0 replies; 4+ messages in thread
From: Richard Cochran @ 2019-07-08 16:39 UTC (permalink / raw)
To: ZhangXiaoxu; +Cc: john.stultz, tglx, sboyd, linux-kernel
On Mon, Jul 08, 2019 at 03:55:04PM +0800, ZhangXiaoxu wrote:
> When covert the usec to nsec, it will multiple 1000, it maybe
> overflow and lead an undefined behavior.
>
> For example, users may input an negative tv_usec values when
> call adjtimex syscall, then multiple 1000 maybe overflow it
> to a positive and legal number.
>
> So, we should validate the usec before coverted it to nsec.
>
> Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
> ---
> kernel/time/timekeeping.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index 44b726b..e5c1d00 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -1272,9 +1272,6 @@ static int timekeeping_inject_offset(const struct timespec64 *ts)
> struct timespec64 tmp;
> int ret = 0;
>
> - if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
> - return -EINVAL;
> -
> raw_spin_lock_irqsave(&timekeeper_lock, flags);
> write_seqcount_begin(&tk_core.seq);
>
> @@ -2321,6 +2318,9 @@ int do_adjtimex(struct __kernel_timex *txc)
>
> if (txc->modes & ADJ_SETOFFSET) {
> struct timespec64 delta;
> +
> + if (txc->time.tv_usec < 0 || txc->time.tv_usec >= USEC_PER_SEC)
> + return -EINVAL;
This test is wrong. If the tv_usec field is in nanoseconds, then the
value can easily be greater than USEC_PER_SEC.
> delta.tv_sec = txc->time.tv_sec;
> delta.tv_nsec = txc->time.tv_usec;
> if (!(txc->modes & ADJ_NANO))
> --
> 2.7.4
>
Thanks,
Richard
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-07-08 7:55 [PATCH] time: Validate the usec before covert to nsec in do_adjtimex ZhangXiaoxu
2019-07-08 9:24 ` Thomas Gleixner
2019-07-08 10:42 ` zhangxiaoxu (A)
2019-07-08 16:39 ` Richard Cochran
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