On 10/11/2020 15:24, Paul E. McKenney wrote:
> On Mon, Nov 09, 2020 at 11:57:15PM -0500, Paul Gortmaker wrote:
>>
>>
>> On 2020-11-09 8:07 p.m., Qian Cai wrote:
>>> On Mon, 2020-11-09 at 13:04 +0000, Colin King wrote:
>>>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>>
>>>> Currently the allocation of cpulist is based on the length of buf but does
>>>> not include the addition end of string '\0' terminator. Static analysis is
>>>> reporting this as a potential out-of-bounds access on cpulist. Fix this by
>>>> allocating enough space for the additional '\0' terminator.
>>>>
>>>> Addresses-Coverity: ("Out-of-bounds access")
>>>> Fixes: 65987e67f7ff ("cpumask: add "last" alias for cpu list specifications")
>>>
>>> Yeah, this bad commit also introduced KASAN errors everywhere and then will
>>> disable lockdep that makes our linux-next CI miserable. Confirmed that this
>>> patch will fix it.
>>
>> I appreciate the reports reminding me why I hate touching string handling.
>>
>> But let us not lose sight of why linux-next exists. We want to
>> encourage code to appear there as a sounding board before it goes
>> mainline, so we can fix things and not pollute mainline git history
>> with those trivialities.
>>
>> If you've decided to internalize linux-next as part of your CI, then
>> great, but do note that does not elevate linux-next to some pristine
>> status for the world at large. That only means you have to watch more
>> closely what is going on.
>>
>> If you want to declare linux-next unbreakable -- well that would scare
>> away others to get the multi-arch or multi-config coverage that they may
>> not be able to do themselves. We are not going to do that.
>>
>> I have (hopefully) fixed the "bad commit" in v2 -- as part of the
>> implicit linux-next rule "you broke it, you better fix it ASAP".
>>
>> But "bad" and "miserable" can be things that might scare people off of
>> making use of linux-next for what it is meant to be for. And I am not
>> OK with that.
>
> They would need to use much stronger language to scare me off. That said,
> what on earth is the point of running tests if they do not from time to
> time find bugs? ;-)
>
> Thanx, Paul
For me, part of the QA process is statically analyzing linux-next to
catch bugs before they land in linux. I think other testing is equally
worth while as catching bugs early saves time and money.
Colin
>
>> Thanks,
>> Paul.
>> --
>>
>>>
>>>> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>> ---
>>>> lib/cpumask.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/lib/cpumask.c b/lib/cpumask.c
>>>> index 34ecb3005941..cb8a3ef0e73e 100644
>>>> --- a/lib/cpumask.c
>>>> +++ b/lib/cpumask.c
>>>> @@ -185,7 +185,7 @@ int __ref cpulist_parse(const char *buf, struct cpumask
>>>> *dstp)
>>>> {
>>>> int r;
>>>> char *cpulist, last_cpu[5]; /* NR_CPUS <= 9999 */
>>>> - size_t len = strlen(buf);
>>>> + size_t len = strlen(buf) + 1;
>>>> bool early = !slab_is_available();
>>>> if (!strcmp(buf, "all")) {
>>>
