KASAN: out-of-bounds Read in __switch_to (2)

KASAN: out-of-bounds Read in __switch_to (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    fb0155a0 Merge tag 'nfs-for-5.9-3' of git://git.linux-nfs...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15147bc3900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=41b736b7ce1b3ea4
dashboard link: https://syzkaller.appspot.com/bug?extid=2667188e965125ab6e7a
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11743a37900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2667188e965125ab6e7a@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in arch_end_context_switch arch/x86/include/asm/paravirt.h:625 [inline]
BUG: KASAN: out-of-bounds in __switch_to+0xddc/0xfe0 arch/x86/kernel/process_64.c:566
Read of size 8 at addr ffffffff89fc6bd8 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:

The buggy address belongs to the variable:
 pv_ops+0x118/0x2c0

Memory state around the buggy address:
 ffffffff89fc6a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff89fc6b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff89fc6b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                       ^
 ffffffff89fc6c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff89fc6c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 0 Comm: swapper/1 Tainted: G    B             5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
Kernel Offset: disabled
Rebooting in 86400 seconds..


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Re: KASAN: out-of-bounds Read in __switch_to (2)

[syzbot]

syzbot suspects this issue was fixed by commit:

commit a49145acfb975d921464b84fe00279f99827d816
Author: George Kennedy <george.kennedy@oracle.com>
Date:   Tue Jul 7 19:26:03 2020 +0000

    fbmem: add margin check to fb_check_caps()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=174684b8500000
start commit:   fb0155a0 Merge tag 'nfs-for-5.9-3' of git://git.linux-nfs...
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=41b736b7ce1b3ea4
dashboard link: https://syzkaller.appspot.com/bug?extid=2667188e965125ab6e7a
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11743a37900000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: fbmem: add margin check to fb_check_caps()

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: KASAN: out-of-bounds Read in __switch_to (2)

[Dmitry Vyukov]

On Thu, Oct 29, 2020 at 3:10 PM syzbot
<syzbot+2667188e965125ab6e7a@syzkaller.appspotmail.com> wrote:
>
> syzbot suspects this issue was fixed by commit:
>
> commit a49145acfb975d921464b84fe00279f99827d816
> Author: George Kennedy <george.kennedy@oracle.com>
> Date:   Tue Jul 7 19:26:03 2020 +0000
>
>     fbmem: add margin check to fb_check_caps()
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=174684b8500000
> start commit:   fb0155a0 Merge tag 'nfs-for-5.9-3' of git://git.linux-nfs...
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=41b736b7ce1b3ea4
> dashboard link: https://syzkaller.appspot.com/bug?extid=2667188e965125ab6e7a
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11743a37900000
>
> If the result looks correct, please mark the issue as fixed by replying with:
>
> #syz fix: fbmem: add margin check to fb_check_caps()
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

#syz fix: fbmem: add margin check to fb_check_caps()