linux-kernel - Re: [syzbot] KASAN: slab-out-of-bounds Read in riscv_intc_irq

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Date:   Thu, 18 Mar 2021 15:11:03 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     syzbot <syzbot+005654dd9b8f26bd4c07@...kaller.appspotmail.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Marc Zyngier <maz@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [syzbot] KASAN: slab-out-of-bounds Read in riscv_intc_irq

On Thu, Mar 18, 2021 at 1:21 PM Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
> On 2021/3/14 18:47, Dmitry Vyukov wrote:
> > On Sun, Mar 14, 2021 at 11:14 AM syzbot
> > <syzbot+005654dd9b8f26bd4c07@...kaller.appspotmail.com> wrote:
> >> Hello,
> >>
> >> syzbot found the following issue on:
> >>
> >> HEAD commit:    0d7588ab riscv: process: Fix no prototype for arch_dup_tas..
> >> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=15a35756d00000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=81c0b708b31626cc
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=005654dd9b8f26bd4c07
> >> userspace arch: riscv64
> >>
> >> 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+005654dd9b8f26bd4c07@...kaller.appspotmail.com
> >>
> >> ==================================================================
> >> BUG: KASAN: slab-out-of-bounds in riscv_intc_irq+0x24/0xcc drivers/irqchip/irq-riscv-intc.c:24
> >> Read of size 8 at addr ffffffe00c963bd0 by task kworker/1:1/4388
> >>
> >> CPU: 1 PID: 4388 Comm: kworker/1:1 Not tainted 5.12.0-rc2-syzkaller-00467-g0d7588ab9ef9 #0
> >> Hardware name: riscv-virtio,qemu (DT)
> >> Workqueue: events nsim_dev_trap_report_work
> >> Call Trace:
> >> [<ffffffe0000096c0>] walk_stackframe+0x0/0x23c arch/riscv/kernel/traps.c:201
> >>
> >> Allocated by task 76347056:
> >> (stack is not available)
> >>
> >> Last potentially related work creation:
> > There seems to be some issue with riscv stack unwinder.
> > This does not have stacks.
>
> Hi, could you test with the following  patch about the no stack
> issue(from v5.11-rc4), I made a mistake when do some cleanup...
>
> https://lore.kernel.org/linux-riscv/ce5b3533-b75d-c31c-4319-9d29769bbbd5@huawei.com/T/#t

Hi Kefeng,

Please see:
http://bit.do/syzbot#no-custom-patches

Is a unit-test for this possible? Fuzzing is not a replacement for unit testing.

> > "BUG: unable to handle kernel access to user memory in schedule_tail"
> > does not have proper stacks:
> > https://syzkaller.appspot.com/bug?id=9de8c24d24004fd5e482555f5ad8314da2fb1cee
> >
> > I also found 2 riscv reports in "KASAN: use-after-free Read in
> > idr_for_each (2)":
> > https://syzkaller.appspot.com/bug?id=7f84dfc3902878befc22e52eb5c7298d0ad70cf3
> >
> > both don't have any stacks:
> >
> > ==================================================================
> > BUG: KASAN: use-after-free in radix_tree_next_slot
> > include/linux/radix-tree.h:422 [inline]
> > BUG: KASAN: use-after-free in idr_for_each+0xf4/0x160 lib/idr.c:202
> > Read of size 8 at addr ffffffe010c00878 by task syz-executor.1/4828
> >
> > CPU: 0 PID: 4828 Comm: syz-executor.1 Not tainted
> > 5.12.0-rc2-syzkaller-00467-g0d7588ab9ef9 #0
> > Hardware name: riscv-virtio,qemu (DT)
> > Call Trace:
> > [<ffffffe0000096c0>] walk_stackframe+0x0/0x23c arch/riscv/kernel/traps.c:201
> >
> > Allocated by task 4828:
> > (stack is not available)
> >
> > Freed by task 4473:
> > (stack is not available)
> >
> >
> >> ---
> >> This report is generated by a bot. It may contain errors.
> >> See https://goo.gl/tpsmEJ for more information about syzbot.
> >> syzbot engineers can be reached at syzkaller@...glegroups.com.
> >>
> >> syzbot will keep track of this issue. See:
> >> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv

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