linux-kernel - [syzbot] BUG: unable to handle kernel paging request in eventfd_ctx

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Message-ID: <00000000000040201f05e96adc81@google.com>
Date:   Sat, 24 Sep 2022 04:47:34 -0700
From:   syzbot <syzbot+6f0c896c5a9449a10ded@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] BUG: unable to handle kernel paging request in eventfd_ctx_put

Hello,

syzbot found the following issue on:

HEAD commit:    521a547ced64 Linux 6.0-rc6
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=134ea35f080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=122d7bd4fc8e0ecb
dashboard link: https://syzkaller.appspot.com/bug?extid=6f0c896c5a9449a10ded
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=149bfdd8880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=104808b0880000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6f0c896c5a9449a10ded@...kaller.appspotmail.com

L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.
BUG: unable to handle page fault for address: ffffffffffffffea
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD bc8f067 P4D bc8f067 PUD bc91067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 3606 Comm: syz-executor343 Not tainted 6.0.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
RIP: 0010:arch_atomic_fetch_sub arch/x86/include/asm/atomic.h:190 [inline]
RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline]
RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:272 [inline]
RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:315 [inline]
RIP: 0010:refcount_dec_and_test include/linux/refcount.h:333 [inline]
RIP: 0010:kref_put include/linux/kref.h:64 [inline]
RIP: 0010:eventfd_ctx_put+0x1e/0x110 fs/eventfd.c:112
Code: ff ff e8 65 7e dc ff e9 b5 fb ff ff 41 54 55 48 89 fd 53 bb ff ff ff ff e8 ef 1d 90 ff be 04 00 00 00 48 89 ef e8 72 80 dc ff <f0> 0f c1 5d 00 bf 01 00 00 00 89 de e8 91 1a 90 ff 83 fb 01 74 35
RSP: 0018:ffffc9000365f748 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff81ebeb3e
RDX: fffffbfffffffffe RSI: 0000000000000004 RDI: ffffffffffffffea
RBP: ffffffffffffffea R08: 0000000000000001 R09: ffffffffffffffed
R10: fffffbfffffffffd R11: 0000000000000000 R12: 0000000000000003
R13: ffffffffffffffea R14: ffffc900037b1000 R15: 00000000ffffffea
FS:  0000555556297300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffea CR3: 0000000072461000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kvm_xen_eventfd_assign arch/x86/kvm/xen.c:1721 [inline]
 kvm_xen_setattr_evtchn arch/x86/kvm/xen.c:1780 [inline]
 kvm_xen_hvm_set_attr+0x563/0x1610 arch/x86/kvm/xen.c:486
 kvm_arch_vm_ioctl+0xe39/0x18b0 arch/x86/kvm/x86.c:6790
 kvm_vm_ioctl+0x15df/0x2380 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4811
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd65dc84b69
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc633540b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd65dc84b69
RDX: 0000000020000040 RSI: 000000004048aec9 RDI: 0000000000000004
RBP: 00007fd65dc48d10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd65dc48da0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: ffffffffffffffea
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_fetch_sub arch/x86/include/asm/atomic.h:190 [inline]
RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:177 [inline]
RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:272 [inline]
RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:315 [inline]
RIP: 0010:refcount_dec_and_test include/linux/refcount.h:333 [inline]
RIP: 0010:kref_put include/linux/kref.h:64 [inline]
RIP: 0010:eventfd_ctx_put+0x1e/0x110 fs/eventfd.c:112
Code: ff ff e8 65 7e dc ff e9 b5 fb ff ff 41 54 55 48 89 fd 53 bb ff ff ff ff e8 ef 1d 90 ff be 04 00 00 00 48 89 ef e8 72 80 dc ff <f0> 0f c1 5d 00 bf 01 00 00 00 89 de e8 91 1a 90 ff 83 fb 01 74 35
RSP: 0018:ffffc9000365f748 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff81ebeb3e
RDX: fffffbfffffffffe RSI: 0000000000000004 RDI: ffffffffffffffea
RBP: ffffffffffffffea R08: 0000000000000001 R09: ffffffffffffffed
R10: fffffbfffffffffd R11: 0000000000000000 R12: 0000000000000003
R13: ffffffffffffffea R14: ffffc900037b1000 R15: 00000000ffffffea
FS:  0000555556297300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffea CR3: 0000000072461000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	e8 65 7e dc ff       	callq  0xffdc7e6a
   5:	e9 b5 fb ff ff       	jmpq   0xfffffbbf
   a:	41 54                	push   %r12
   c:	55                   	push   %rbp
   d:	48 89 fd             	mov    %rdi,%rbp
  10:	53                   	push   %rbx
  11:	bb ff ff ff ff       	mov    $0xffffffff,%ebx
  16:	e8 ef 1d 90 ff       	callq  0xff901e0a
  1b:	be 04 00 00 00       	mov    $0x4,%esi
  20:	48 89 ef             	mov    %rbp,%rdi
  23:	e8 72 80 dc ff       	callq  0xffdc809a
* 28:	f0 0f c1 5d 00       	lock xadd %ebx,0x0(%rbp) <-- trapping instruction
  2d:	bf 01 00 00 00       	mov    $0x1,%edi
  32:	89 de                	mov    %ebx,%esi
  34:	e8 91 1a 90 ff       	callq  0xff901aca
  39:	83 fb 01             	cmp    $0x1,%ebx
  3c:	74 35                	je     0x73


---
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