[syzbot] general protection fault in iomap_dio_bio_iter

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4fafd96910ad Add linux-next specific files for 20230203
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=148cef45480000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d2fba7d42502ca4
dashboard link: https://syzkaller.appspot.com/bug?extid=a4f579527ea6394140a5
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=1245a3c3480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132bfad9480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/348cc2da441a/disk-4fafd969.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e2dedc500f12/vmlinux-4fafd969.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fae710d9ebd8/bzImage-4fafd969.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4f579...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 PID: 5141 Comm: syz-executor393 Not tainted 6.2.0-rc6-next-20230203-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
RIP: 0010:iov_iter_reexpand include/linux/uio.h:299 [inline]
RIP: 0010:iomap_dio_bio_iter+0xa44/0x1440 fs/iomap/direct-io.c:373
Code: 6c 24 38 48 c1 ea 03 80 3c 02 00 0f 85 5b 08 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 5d 40 48 8d 7b 10 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f9 07 00 00 4c 8b 7c 24 38 31 ff 48 89 6b 10 4c
RSP: 0018:ffffc90003eaf638 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff820211f4 RDI: 0000000000000010
RBP: 000000000000ee00 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801ccc0640
R13: ffff888029cea000 R14: ffffc90003eaf828 R15: ffffc90003eaf828
FS: 00007f0424eb1700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0424e90718 CR3: 000000007ab39000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
iomap_dio_iter fs/iomap/direct-io.c:436 [inline]
__iomap_dio_rw+0xd81/0x1d80 fs/iomap/direct-io.c:594
iomap_dio_rw+0x40/0xa0 fs/iomap/direct-io.c:682
ext4_dio_read_iter fs/ext4/file.c:94 [inline]
ext4_file_read_iter+0x4be/0x690 fs/ext4/file.c:145
call_read_iter include/linux/fs.h:1845 [inline]
generic_file_splice_read+0x182/0x4b0 fs/splice.c:309
do_splice_to+0x1b9/0x240 fs/splice.c:793
splice_direct_to_actor+0x2ab/0x8a0 fs/splice.c:865
do_splice_direct+0x1ab/0x280 fs/splice.c:974
do_sendfile+0xb19/0x12c0 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64 fs/read_write.c:1309 [inline]
__x64_sys_sendfile64+0x1d0/0x210 fs/read_write.c:1309
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: 0033:0x7f0424f212a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0424eb12f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f0424faa4d0 RCX: 00007f0424f212a9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 00007f0424f7727c R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffff04 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 00007f0424f77078 R14: 0000000020000600 R15: 00007f0424faa4d8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:iov_iter_reexpand include/linux/uio.h:299 [inline]
RIP: 0010:iomap_dio_bio_iter+0xa44/0x1440 fs/iomap/direct-io.c:373
Code: 6c 24 38 48 c1 ea 03 80 3c 02 00 0f 85 5b 08 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 5d 40 48 8d 7b 10 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f9 07 00 00 4c 8b 7c 24 38 31 ff 48 89 6b 10 4c
RSP: 0018:ffffc90003eaf638 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff820211f4 RDI: 0000000000000010
RBP: 000000000000ee00 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88801ccc0640
R13: ffff888029cea000 R14: ffffc90003eaf828 R15: ffffc90003eaf828
FS: 00007f0424eb1700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0424f46d30 CR3: 000000007ab39000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 6c insb (%dx),%es:(%rdi)
1: 24 38 and $0x38,%al
3: 48 c1 ea 03 shr $0x3,%rdx
7: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
b: 0f 85 5b 08 00 00 jne 0x86c
11: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
18: fc ff df
1b: 49 8b 5d 40 mov 0x40(%r13),%rbx
1f: 48 8d 7b 10 lea 0x10(%rbx),%rdi
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 f9 07 00 00 jne 0x82d
34: 4c 8b 7c 24 38 mov 0x38(%rsp),%r15
39: 31 ff xor %edi,%edi
3b: 48 89 6b 10 mov %rbp,0x10(%rbx)
3f: 4c rex.WR


---
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[Hillf Danton]

On Tue, 07 Feb 2023 16:21:58 -0800

> syzbot found the following issue on:
>
> HEAD commit: 4fafd96910ad Add linux-next specific files for 20230203
> git tree: linux-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132bfad9480000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git iov-extract-20230207

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5566 } 2654 jiffies s: 2877 root: 0x0/T
rcu: blocking rcu_node structures (internal RCU debug):


Tested on:

commit: 986f457b block: convert bio_map_user_iov to use iov_it..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git iov-extract-20230207
console output: https://syzkaller.appspot.com/x/log.txt?x=1218381f480000
kernel config: https://syzkaller.appspot.com/x/.config?x=6bb1911ff9919df0

dashboard link: https://syzkaller.appspot.com/bug?extid=a4f579527ea6394140a5
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.