Re: [syzbot] BUG: RESTRACK detected leak of resources

[Haakon Bugge]

> On 4 Oct 2021, at 15:22, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> 
> On Mon, 4 Oct 2021 at 15:15, Jason Gunthorpe <jgg@xxxxxxxx> wrote:
>> 
>> On Mon, Oct 04, 2021 at 02:42:11PM +0200, Dmitry Vyukov wrote:
>>> On Mon, 4 Oct 2021 at 12:45, syzbot
>>> <syzbot+3a992c9e4fd9f0e6fd0e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>>> 
>>>> Hello,
>>>> 
>>>> syzbot found the following issue on:
>>>> 
>>>> HEAD commit:    c7b4d0e56a1d Add linux-next specific files for 20210930
>>>> git tree:       linux-next
>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=104be6cb300000
>>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=c9a1f6685aeb48bd
>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=3a992c9e4fd9f0e6fd0e
>>>> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>>>> 
>>>> Unfortunately, I don't have any reproducer for this issue yet.
>>>> 
>>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>>> Reported-by: syzbot+3a992c9e4fd9f0e6fd0e@xxxxxxxxxxxxxxxxxxxxxxxxx
>>> 
>>> +RESTRACK maintainers
>>> 
>>> (it would also be good if RESTRACK would print a more standard oops
>>> with stack/filenames, so that testing systems can attribute issues to
>>> files/maintainers).
>> 
>> restrack certainly should trigger a WARN_ON to stop the kernel.. But I
>> don't know what stack track would be useful here. The culprit is
>> always the underlying driver, not the core code..
> 
> There seems to be a significant overlap between
> drivers/infiniband/core/restrack.c and drivers/infiniband/sw/rxe/rxe.c
> maintainers, so perhaps restrack.c is good enough approximation to
> extract relevant people (definitely better then no CC at all :))

Looks to me as this is rxe:

[ 1892.778632][ T8958] BUG: KASAN: use-after-free in __rxe_drop_index_locked+0xb5/0x100
[snip]
[ 1892.822375][ T8958] Call Trace:
[ 1892.825655][ T8958]  <TASK>
[ 1892.828594][ T8958]  dump_stack_lvl+0xcd/0x134
[ 1892.833273][ T8958]  print_address_description.constprop.0.cold+0x6c/0x30c
[ 1892.840316][ T8958]  ? __rxe_drop_index_locked+0xb5/0x100
[ 1892.845864][ T8958]  ? __rxe_drop_index_locked+0xb5/0x100
[ 1892.851424][ T8958]  kasan_report.cold+0x83/0xdf
[ 1892.856200][ T8958]  ? __rxe_drop_index_locked+0xb5/0x100
[ 1892.861761][ T8958]  kasan_check_range+0x13d/0x180
[ 1892.866780][ T8958]  __rxe_drop_index_locked+0xb5/0x100
[ 1892.872164][ T8958]  __rxe_drop_index+0x3f/0x60
[ 1892.876850][ T8958]  rxe_dereg_mr+0x14b/0x240
[ 1892.881381][ T8958]  ib_dealloc_pd_user+0x96/0x230
[ 1892.886566][ T8958]  rds_ib_dev_free+0xd4/0x3a0

So, RDS de-allocs its PD, ib core must first de-register the PD's local MR, calls rxe_dereg_mr(), ...


Thxs, Håkon


> 
>> Anyhow, this report is either rxe or rds by the look of it.
>> 
>> Jason