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

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Message-ID: <000000000000a6b67d05f43a9854@google.com>
Date:   Wed, 08 Feb 2023 17:49:49 -0800
From:   syzbot <syzbot+d632e24db18585d7b3c6@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, llvm@...ts.linux.dev, mike.kravetz@...cle.com,
        muchun.song@...ux.dev, nathan@...nel.org, ndesaulniers@...gle.com,
        syzkaller-bugs@...glegroups.com, trix@...hat.com
Subject: Re: [syzbot] BUG: unable to handle kernel paging request in folio_flags

syzbot has found a reproducer for the following issue on:

HEAD commit:    38d2b86a665b Add linux-next specific files for 20230208
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15f5e3a7480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3691b32dd4410e01
dashboard link: https://syzkaller.appspot.com/bug?extid=d632e24db18585d7b3c6
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=1454ddf3480000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14a8431f480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0a9d60e90514/disk-38d2b86a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/71311be5f1a1/vmlinux-38d2b86a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a242870cc8eb/bzImage-38d2b86a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d632e24db18585d7b3c6@...kaller.appspotmail.com

memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=5080 'syz-executor561'
BUG: unable to handle page fault for address: ffffffffffffffed
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD c570067 P4D c570067 PUD c572067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 5080 Comm: syz-executor561 Not tainted 6.2.0-rc7-next-20230208-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
RIP: 0010:PageTail include/linux/page-flags.h:290 [inline]
RIP: 0010:folio_flags.constprop.0+0x2c/0x150 include/linux/page-flags.h:317
Code: 49 89 fc 55 53 e8 84 4e b7 ff 49 8d 7c 24 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 f8 00 00 00 <49> 8b 5c 24 08 31 ff 83 e3 01 48 89 de e8 c2 4a b7 ff 48 85 db 0f
RSP: 0018:ffffc90003cbfc08 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffffffffffffe5 RCX: 0000000000000000
RDX: 1ffffffffffffffd RSI: ffffffff81cd1f5c RDI: ffffffffffffffed
RBP: ffffffffffffffe5 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffffe5 R11: 0000000000000000 R12: ffffffffffffffe5
R13: 000feffffff00000 R14: 0000000000000046 R15: 000feffffff00000
FS:  0000555556e84300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffed CR3: 000000002bb37000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 folio_test_head include/linux/page-flags.h:781 [inline]
 folio_test_large include/linux/page-flags.h:802 [inline]
 PageHeadHuge+0x18/0xc0 mm/hugetlb.c:2060
 folio_test_hugetlb include/linux/page-flags.h:830 [inline]
 folio_file_page include/linux/pagemap.h:702 [inline]
 shmem_read_mapping_page_gfp+0x34/0x100 mm/shmem.c:4366
 shmem_read_mapping_page include/linux/shmem_fs.h:124 [inline]
 udmabuf_create+0x93b/0x1440 drivers/dma-buf/udmabuf.c:286
 udmabuf_ioctl_create drivers/dma-buf/udmabuf.c:346 [inline]
 udmabuf_ioctl+0x156/0x2c0 drivers/dma-buf/udmabuf.c:377
 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+0x197/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fb0a3f40bb9
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:00007ffd5ab9a6e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb0a3f40bb9
RDX: 0000000020000080 RSI: 0000000040187542 RDI: 0000000000000005
RBP: 00007fb0a3f04d60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb0a3f04df0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: ffffffffffffffed
---[ end trace 0000000000000000 ]---
RIP: 0010:PageTail include/linux/page-flags.h:290 [inline]
RIP: 0010:folio_flags.constprop.0+0x2c/0x150 include/linux/page-flags.h:317
Code: 49 89 fc 55 53 e8 84 4e b7 ff 49 8d 7c 24 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 f8 00 00 00 <49> 8b 5c 24 08 31 ff 83 e3 01 48 89 de e8 c2 4a b7 ff 48 85 db 0f
RSP: 0018:ffffc90003cbfc08 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffffffffffffffe5 RCX: 0000000000000000
RDX: 1ffffffffffffffd RSI: ffffffff81cd1f5c RDI: ffffffffffffffed
RBP: ffffffffffffffe5 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffffe5 R11: 0000000000000000 R12: ffffffffffffffe5
R13: 000feffffff00000 R14: 0000000000000046 R15: 000feffffff00000
FS:  0000555556e84300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffed CR3: 000000002bb37000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	49 89 fc             	mov    %rdi,%r12
   3:	55                   	push   %rbp
   4:	53                   	push   %rbx
   5:	e8 84 4e b7 ff       	callq  0xffb74e8e
   a:	49 8d 7c 24 08       	lea    0x8(%r12),%rdi
   f:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  16:	fc ff df
  19:	48 89 fa             	mov    %rdi,%rdx
  1c:	48 c1 ea 03          	shr    $0x3,%rdx
  20:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
  24:	0f 85 f8 00 00 00    	jne    0x122
* 2a:	49 8b 5c 24 08       	mov    0x8(%r12),%rbx <-- trapping instruction
  2f:	31 ff                	xor    %edi,%edi
  31:	83 e3 01             	and    $0x1,%ebx
  34:	48 89 de             	mov    %rbx,%rsi
  37:	e8 c2 4a b7 ff       	callq  0xffb74afe
  3c:	48 85 db             	test   %rbx,%rbx
  3f:	0f                   	.byte 0xf