On Wed, Oct 27, 2021 at 08:20:08PM +0200, Laurent Vivier wrote: > On 27/10/2021 19:03, Laurent Vivier wrote: > > On 27/10/2021 18:25, Laurent Vivier wrote: > > > On 27/10/2021 17:28, Michael S. Tsirkin wrote: > > > > On Wed, Oct 27, 2021 at 03:36:19PM +0200, Dmitry Vyukov wrote: > > > > > On Wed, 27 Oct 2021 at 15:11, Laurent Vivier <lvivier@xxxxxxxxxx> wrote: > > > > > > > > > > > > On 26/10/2021 18:39, syzbot wrote: > > > > > > > Hello, > > > > > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > > > > > HEAD commit: 9ae1fbdeabd3 Add linux-next specific files for 20211025 > > > > > > > git tree: linux-next > > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1331363cb00000 > > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=aeb17e42bc109064 > > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=b86736b5935e0d25b446 > > > > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 > > > > > > > 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ce954b00000 > > > > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132fcf62b00000 > > > > > > > > > > > > > > The issue was bisected to: > > > > > > > > > > > > > > commit 22849b5ea5952d853547cc5e0651f34a246b2a4f > > > > > > > Author: Leon Romanovsky <leonro@xxxxxxxxxx> > > > > > > > Date: Thu Oct 21 14:16:14 2021 +0000 > > > > > > > > > > > > > > devlink: Remove not-executed trap policer notifications > > > > > > > > > > > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=137d8bfcb00000 > > > > > > > final oops: https://syzkaller.appspot.com/x/report.txt?x=10fd8bfcb00000 > > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=177d8bfcb00000 > > > > > > > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > > > > Reported-by: syzbot+b86736b5935e0d25b446@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > > Fixes: 22849b5ea595 ("devlink: Remove not-executed trap policer notifications") > > > > > > > > > > > > > > ================================================================== > > > > > > > BUG: KASAN: slab-out-of-bounds in memcpy include/linux/fortify-string.h:225 [inline] > > > > > > > BUG: KASAN: slab-out-of-bounds in > > > > > > > copy_data+0xf3/0x2e0 > > > > > > > drivers/char/hw_random/virtio-rng.c:68 > > > > > > > Read of size 64 at addr ffff88801a7a1580 by task syz-executor989/6542 > > > > > > > > > > > > > > > > > > > I'm not able to reproduce the problem with next-20211026 and the C reproducer. > > > > > > > > > > > > And reviewing the code in copy_data() I don't see any issue. > > > > > > > > > > > > Is it possible to know what it the VM configuration used to test it? > > > > > > > > > > Hi Laurent, > > > > > > > > > > syzbot used e2-standard-2 GCE VM when that happened. > > > > > You can see some info about these VMs under the "VM info" link on the dashboard. > > > > > > > > Could you pls confirm whether reverting > > > > caaf2874ba27b92bca6f0298bf88bad94067ec37 addresses this? > > > > > > > > > > I've restarted the syzbot on top of "hwrng: virtio - don't wait on > > > cleanup" [1] and the problem has not been triggered. > > > > > > See https://syzkaller.appspot.com/bug?extid=b86736b5935e0d25b446 > > > > The problem seems to be introduced by the last patch: > > > > "hwrng: virtio - always add a pending request" > > I think I understand the problem. > > As we check data_avail != 0 before waiting on the completion, we can have a data_idx != 0. > > The following change fixes the problem for me: > > --- a/drivers/char/hw_random/virtio-rng.c > +++ b/drivers/char/hw_random/virtio-rng.c > @@ -52,6 +52,8 @@ static void request_entropy(struct virtrng_info *vi) > struct scatterlist sg; > > reinit_completion(&vi->have_data); > + vi->data_avail = 0; > + vi->data_idx = 0; > > sg_init_one(&sg, vi->data, sizeof(vi->data)); > > > MST, do you update the patch or do you want I send a new version? > > Thanks, > Laurent New version of the patchset pls, and note in the changelog that just this patch changed. -- MST
