Re: [moderation/CI] Re: minix: convert to iomap and add direct I/O

#syz upstream

On Fri, Jun 26, 2026 at 4:09 AM syzbot ci
<[email protected]> wrote:
>
> syzbot ci has tested the following series
>
> [v1] minix: convert to iomap and add direct I/O
> https://lore.kernel.org/all/[email protected]
> * [PATCH 1/3] minix: add iomap infrastructure
> * [PATCH 2/3] minix: convert address space operations to iomap
> * [PATCH 3/3] minix: convert file operations to iomap and add direct I/O
>
> and found the following issues:
> * BUG: unable to handle kernel NULL pointer dereference in page_symlink
> * WARNING in block_truncate_page
> * WARNING in iomap_writeback_folio
> * general protection fault in minix_read_folio
>
> Full report is available here:
> https://ci.syzbot.org/series/5741f2fe-e35f-460c-b8ae-d02789a43a3a
>
> ***
>
> BUG: unable to handle kernel NULL pointer dereference in page_symlink
>
> tree:      torvalds
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      ab9de95c9cf952332ab79453b4b5d1bfca8e514f
> arch:      amd64
> compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
> config:    https://ci.syzbot.org/builds/3e5d737a-bbd5-4a7b-9ad1-4a77f3c42b23/config
> syz repro: https://ci.syzbot.org/findings/6370c479-1d88-4203-ab64-5ce5413cc836/syz_repro
>
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> #PF: supervisor instruction fetch in kernel mode
> #PF: error_code(0x0010) - not-present page
> PGD 800000016c223067 P4D 800000016c223067 PUD 0
> Oops: Oops: 0010 [#1] SMP KASAN PTI
> CPU: 1 UID: 0 PID: 5877 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:0x0
> Code: Unable to access opcode bytes at 0xffffffffffffffd6.
> RSP: 0018:ffffc90003a3fc18 EFLAGS: 00010246
> RAX: 1ffffffff17ce4d0 RBX: ffffffff8be72680 RCX: 0000000000000008
> RDX: 0000000000000000 RSI: ffff8881b4c23820 RDI: 0000000000000000
> RBP: ffffc90003a3fd48 R08: ffffc90003a3fcc0 R09: ffffc90003a3fce0
> R10: 000000000000000b R11: 0000000000000000 R12: ffff88816cfec218
> R13: 1ffffffff17ce4d1 R14: 0000000000000008 R15: dffffc0000000000
> FS:  00007fc3dc9f66c0(0000) GS:ffff8882a9227000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffffffffffffd6 CR3: 000000016bc24000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  page_symlink+0x27a/0x440 fs/namei.c:6418
>  minix_symlink+0xcc/0x150 fs/minix/namei.c:87
>  vfs_symlink+0x18b/0x330 fs/namei.c:5656
>  filename_symlinkat+0x1cd/0x410 fs/namei.c:5681
>  __do_sys_symlink fs/namei.c:5708 [inline]
>  __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5704
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fc3dd39ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fc3dc9f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
> RAX: ffffffffffffffda RBX: 00007fc3dd615fa0 RCX: 00007fc3dd39ce59
> RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 0000200000000100
> RBP: 00007fc3dd432e6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fc3dd616038 R14: 00007fc3dd615fa0 R15: 00007ffc9f986118
>  </TASK>
> Modules linked in:
> CR2: 0000000000000000
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:0x0
> Code: Unable to access opcode bytes at 0xffffffffffffffd6.
> RSP: 0018:ffffc90003a3fc18 EFLAGS: 00010246
> RAX: 1ffffffff17ce4d0 RBX: ffffffff8be72680 RCX: 0000000000000008
> RDX: 0000000000000000 RSI: ffff8881b4c23820 RDI: 0000000000000000
> RBP: ffffc90003a3fd48 R08: ffffc90003a3fcc0 R09: ffffc90003a3fce0
> R10: 000000000000000b R11: 0000000000000000 R12: ffff88816cfec218
> R13: 1ffffffff17ce4d1 R14: 0000000000000008 R15: dffffc0000000000
> FS:  00007fc3dc9f66c0(0000) GS:ffff8882a9227000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffffffffffffd6 CR3: 000000016bc24000 CR4: 00000000000006f0
>
>
> ***
>
> WARNING in block_truncate_page
>
> tree:      torvalds
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      ab9de95c9cf952332ab79453b4b5d1bfca8e514f
> arch:      amd64
> compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
> config:    https://ci.syzbot.org/builds/3e5d737a-bbd5-4a7b-9ad1-4a77f3c42b23/config
> syz repro: https://ci.syzbot.org/findings/a5a50111-30c6-4d8b-876d-586b3b49470f/syz_repro
>
> loop0: detected capacity change from 0 to 64
> ------------[ cut here ]------------
> bh->b_size != blocksize
> WARNING: fs/buffer.c:2696 at block_truncate_page+0x70a/0x830 fs/buffer.c:2696, CPU#0: syz.0.17/5866
> Modules linked in:
> CPU: 0 UID: 0 PID: 5866 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:block_truncate_page+0x70a/0x830 fs/buffer.c:2696
> Code: 5c d0 6a ff 89 e8 48 83 c4 40 5b 41 5c 41 5d 41 5e 41 5f 5d e9 c7 05 5b 09 cc e8 41 d0 6a ff e9 51 ff ff ff e8 37 d0 6a ff 90 <0f> 0b 90 e9 76 fc ff ff 44 89 f1 80 e1 07 38 c1 0f 8c 50 f9 ff ff
> RSP: 0018:ffffc90003a8f9e8 EFLAGS: 00010293
> RAX: ffffffff825b6069 RBX: 0000000000000003 RCX: ffff888113619dc0
> RDX: 0000000000000000 RSI: 0000000000000400 RDI: ffffffff93ef90a0
> RBP: 0000000000000000 R08: ffff88810b3f1d07 R09: 1ffff1102167e3a0
> R10: dffffc0000000000 R11: ffffed102167e3a1 R12: 0000000000000400
> R13: ffff88810b3f1d00 R14: ffffffff93ef90a0 R15: 1ffff1102167e3a0
> FS:  00007f743592d6c0(0000) GS:ffff88818dc27000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b33163fff CR3: 0000000021428000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  truncate fs/minix/itree_common.c:314 [inline]
>  V2_minix_truncate+0x22d/0x1150 fs/minix/itree_v2.c:73
>  minix_setattr+0x14f/0x1a0 fs/minix/file.c:195
>  notify_change+0xbba/0xea0 fs/attr.c:556
>  do_truncate+0x1c2/0x250 fs/open.c:68
>  do_ftruncate+0x4d4/0x580 fs/open.c:194
>  ksys_ftruncate fs/open.c:206 [inline]
>  __do_sys_ftruncate fs/open.c:211 [inline]
>  __se_sys_ftruncate fs/open.c:209 [inline]
>  __x64_sys_ftruncate+0x8f/0xe0 fs/open.c:209
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f743499ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f743592d028 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
> RAX: ffffffffffffffda RBX: 00007f7434c15fa0 RCX: 00007f743499ce59
> RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000004
> RBP: 00007f7434a32e6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f7434c16038 R14: 00007f7434c15fa0 R15: 00007ffd57fa9d88
>  </TASK>
>
>
> ***
>
> WARNING in iomap_writeback_folio
>
> tree:      torvalds
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      ab9de95c9cf952332ab79453b4b5d1bfca8e514f
> arch:      amd64
> compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
> config:    https://ci.syzbot.org/builds/3e5d737a-bbd5-4a7b-9ad1-4a77f3c42b23/config
> syz repro: https://ci.syzbot.org/findings/faeadbdc-8f36-45bd-b9df-40b83300c68d/syz_repro
>
> ------------[ cut here ]------------
> atomic_read(&ifs->write_bytes_pending) != 0
> WARNING: fs/iomap/buffered-io.c:1828 at iomap_writeback_init fs/iomap/buffered-io.c:1828 [inline], CPU#1: kworker/u10:5/4737
> WARNING: fs/iomap/buffered-io.c:1828 at iomap_writeback_folio+0x20f6/0x2790 fs/iomap/buffered-io.c:1974, CPU#1: kworker/u10:5/4737
> Modules linked in:
> CPU: 1 UID: 0 PID: 4737 Comm: kworker/u10:5 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Workqueue: writeback wb_workfn (flush-7:0)
> RIP: 0010:iomap_writeback_init fs/iomap/buffered-io.c:1828 [inline]
> RIP: 0010:iomap_writeback_folio+0x20f6/0x2790 fs/iomap/buffered-io.c:1974
> Code: e8 4f 96 5b ff 48 8d 3d 28 c1 ce 0d 67 48 0f b9 3a e9 da e3 ff ff e8 39 96 5b ff 90 0f 0b 90 e9 4b e5 ff ff e8 2b 96 5b ff 90 <0f> 0b 90 e9 cc e8 ff ff e8 1d 96 5b ff bf e4 ff ff ff 44 89 ee e8
> RSP: 0018:ffffc90003e3ef80 EFLAGS: 00010293
> RAX: ffffffff826a9a75 RBX: 00000000ffff8881 RCX: ffff88816b235940
> RDX: 0000000000000000 RSI: 00000000ffff8881 RDI: 0000000000000000
> RBP: 1ffff11036dd96d9 R08: ffff8881babac587 R09: 1ffff110375758b0
> R10: dffffc0000000000 R11: ffffed10375758b1 R12: 1ffff110375758b0
> R13: 000000000000000a R14: ffff8881babac584 R15: ffffea0006bc8ac0
> FS:  0000000000000000(0000) GS:ffff8882a9227000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005555779c0a28 CR3: 0000000113804000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  iomap_writepages+0x167/0x2e0 fs/iomap/buffered-io.c:2051
>  minix_writepages+0xef/0x160 fs/minix/inode.c:488
>  do_writepages+0x338/0x560 mm/page-writeback.c:2571
>  __writeback_single_inode+0x12e/0xf90 fs/fs-writeback.c:1787
>  writeback_sb_inodes+0x9de/0x1b00 fs/fs-writeback.c:2079
>  wb_writeback+0x41c/0xad0 fs/fs-writeback.c:2264
>  wb_do_writeback fs/fs-writeback.c:2432 [inline]
>  wb_workfn+0x431/0x10f0 fs/fs-writeback.c:2477
>  process_one_work kernel/workqueue.c:3322 [inline]
>  process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
>  worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
>  kthread+0x388/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
>
>
> ***
>
> general protection fault in minix_read_folio
>
> tree:      torvalds
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      ab9de95c9cf952332ab79453b4b5d1bfca8e514f
> arch:      amd64
> compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
> config:    https://ci.syzbot.org/builds/3e5d737a-bbd5-4a7b-9ad1-4a77f3c42b23/config
> syz repro: https://ci.syzbot.org/findings/fe6b7658-93e2-48c4-8808-28a98a8cc13c/syz_repro
>
> WARNING: The mand mount option has been deprecated and
>          and is ignored by this kernel. Remove the mand
>          option from the mount to silence this warning.
> =======================================================
> Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
> CPU: 1 UID: 0 PID: 5816 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:minix_read_folio+0x8b/0x1d0 fs/minix/inode.c:493
> Code: f1 f1 f8 f8 f8 f8 4b 89 44 25 00 48 b8 f8 f8 f3 f3 f3 f3 f3 f3 4b 89 44 25 08 e8 50 fb 1e ff 49 83 c6 60 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 a6 89 8c ff 4d 8b 36 49 83 c6 28
> RSP: 0018:ffffc9000398f680 EFLAGS: 00010206
> RAX: 000000000000000c RBX: ffffea0006c67fc0 RCX: ffff888102368000
> RDX: 0000000000000000 RSI: ffffea0006c67fc0 RDI: 0000000000000000
> RBP: ffffc9000398f750 R08: ffffea0006c67fc7 R09: 1ffffd4000d8cff8
> R10: dffffc0000000000 R11: ffffffff82a734d0 R12: dffffc0000000000
> R13: 1ffff92000731ed0 R14: 0000000000000060 R15: 1ffffd4000d8cff9
> FS:  00007f5343f936c0(0000) GS:ffff8882a9227000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b33763fff CR3: 00000001be366000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  filemap_read_folio+0x12c/0x3a0 mm/filemap.c:2510
>  do_read_cache_folio+0x354/0x590 mm/filemap.c:4140
>  read_mapping_folio include/linux/pagemap.h:1015 [inline]
>  __page_get_link+0x52/0x300 fs/namei.c:6332
>  page_get_link+0x27/0xc0 fs/namei.c:6362
>  pick_link+0x72f/0xfe0 fs/namei.c:-1
>  step_into_slowpath+0x58a/0x820 fs/namei.c:2127
>  step_into fs/namei.c:2152 [inline]
>  open_last_lookups fs/namei.c:4643 [inline]
>  path_openat+0x224e/0x3830 fs/namei.c:4856
>  do_file_open+0x23e/0x4a0 fs/namei.c:4888
>  do_sys_openat2+0x115/0x200 fs/open.c:1368
>  do_sys_open fs/open.c:1374 [inline]
>  __do_sys_openat fs/open.c:1390 [inline]
>  __se_sys_openat fs/open.c:1385 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1385
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f534319ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f5343f93028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007f5343415fa0 RCX: 00007f534319ce59
> RDX: 00000000000c4842 RSI: 0000200000000300 RDI: ffffffffffffff9c
> RBP: 00007f5343232e6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f5343416038 R14: 00007f5343415fa0 R15: 00007fff456bcb68
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:minix_read_folio+0x8b/0x1d0 fs/minix/inode.c:493
> Code: f1 f1 f8 f8 f8 f8 4b 89 44 25 00 48 b8 f8 f8 f3 f3 f3 f3 f3 f3 4b 89 44 25 08 e8 50 fb 1e ff 49 83 c6 60 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 a6 89 8c ff 4d 8b 36 49 83 c6 28
> RSP: 0018:ffffc9000398f680 EFLAGS: 00010206
> RAX: 000000000000000c RBX: ffffea0006c67fc0 RCX: ffff888102368000
> RDX: 0000000000000000 RSI: ffffea0006c67fc0 RDI: 0000000000000000
> RBP: ffffc9000398f750 R08: ffffea0006c67fc7 R09: 1ffffd4000d8cff8
> R10: dffffc0000000000 R11: ffffffff82a734d0 R12: dffffc0000000000
> R13: 1ffff92000731ed0 R14: 0000000000000060 R15: 1ffffd4000d8cff9
> FS:  00007f5343f936c0(0000) GS:ffff8882a9227000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f53431ea540 CR3: 00000001be366000 CR4: 00000000000006f0
> ----------------
> Code disassembly (best guess):
>    0:   f1                      int1
>    1:   f1                      int1
>    2:   f8                      clc
>    3:   f8                      clc
>    4:   f8                      clc
>    5:   f8                      clc
>    6:   4b 89 44 25 00          mov    %rax,0x0(%r13,%r12,1)
>    b:   48 b8 f8 f8 f3 f3 f3    movabs $0xf3f3f3f3f3f3f8f8,%rax
>   12:   f3 f3 f3
>   15:   4b 89 44 25 08          mov    %rax,0x8(%r13,%r12,1)
>   1a:   e8 50 fb 1e ff          call   0xff1efb6f
>   1f:   49 83 c6 60             add    $0x60,%r14
>   23:   4c 89 f0                mov    %r14,%rax
>   26:   48 c1 e8 03             shr    $0x3,%rax
> * 2a:   42 80 3c 20 00          cmpb   $0x0,(%rax,%r12,1) <-- trapping instruction
>   2f:   74 08                   je     0x39
>   31:   4c 89 f7                mov    %r14,%rdi
>   34:   e8 a6 89 8c ff          call   0xff8c89df
>   39:   4d 8b 36                mov    (%r14),%r14
>   3c:   49 83 c6 28             add    $0x28,%r14
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
>   Tested-by: [email protected]
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at [email protected].
>
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> (should be on a separate line).
>
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