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KASAN: slab-out-of-bounds Write in bch2_dirent_init_name

Status: upstream: reported C repro on 2025/06/17 15:56
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+894877f2c4dd5fdea634@syzkaller.appspotmail.com
Fix commit: bcachefs: Fix padding zeroout when creating casefolded dirents
Patched on: [ci-upstream-linux-next-kasan-gce-root ci-upstream-rust-kasan-gce], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 48d, last: 9h41m
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] KASAN: slab-out-of-bounds Write in bch2_dirent_init_name 0 (2) 2025/07/14 20:42

Sample crash report:
bcachefs (loop0): done starting filesystem
==================================================================
BUG: KASAN: slab-out-of-bounds in bch2_dirent_init_name+0x396/0x8b0 fs/bcachefs/dirent.c:273
Write of size 1985 at addr ffff8881496a3041 by task syz-executor478/5839

CPU: 0 UID: 0 PID: 5839 Comm: syz-executor478 Not tainted 6.16.0-rc6-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 __asan_memset+0x22/0x50 mm/kasan/shadow.c:84
 bch2_dirent_init_name+0x396/0x8b0 fs/bcachefs/dirent.c:273
 bch2_dirent_create_key+0x2a1/0x5f0 fs/bcachefs/dirent.c:315
 bch2_dirent_create+0xc5/0xc80 fs/bcachefs/dirent.c:358
 bch2_link_trans+0x39e/0x560 fs/bcachefs/namei.c:241
 __bch2_link+0x231/0x3f0 fs/bcachefs/fs.c:776
 bch2_link+0x197/0x220 fs/bcachefs/fs.c:805
 vfs_link+0x4ea/0x6e0 fs/namei.c:4863
 do_linkat+0x272/0x560 fs/namei.c:4933
 __do_sys_link fs/namei.c:4967 [inline]
 __se_sys_link fs/namei.c:4965 [inline]
 __x64_sys_link+0x82/0x90 fs/namei.c:4965
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5e63959b19
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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:00007ffee09b8bd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 0031656c69662f2e RCX: 00007f5e63959b19
RDX: 00007f5e63959b19 RSI: 0000200000000240 RDI: 00002000000001c0
RBP: 00007f5e639d25f0 R08: 00005555839934c0 R09: 00005555839934c0
R10: 0000000000005a9b R11: 0000000000000246 R12: 00007ffee09b8c00
R13: 00007ffee09b8e28 R14: 431bde82d7b634db R15: 00007f5e639a203b
 </TASK>

Allocated by task 5839:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_noprof+0x27a/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 __bch2_trans_kmalloc+0x396/0x9d0 fs/bcachefs/btree_iter.c:3242
 bch2_trans_kmalloc_ip fs/bcachefs/btree_iter.h:604 [inline]
 bch2_trans_kmalloc fs/bcachefs/btree_iter.h:616 [inline]
 bch2_dirent_create_key+0x113/0x5f0 fs/bcachefs/dirent.c:298
 bch2_dirent_create+0xc5/0xc80 fs/bcachefs/dirent.c:358
 bch2_link_trans+0x39e/0x560 fs/bcachefs/namei.c:241
 __bch2_link+0x231/0x3f0 fs/bcachefs/fs.c:776
 bch2_link+0x197/0x220 fs/bcachefs/fs.c:805
 vfs_link+0x4ea/0x6e0 fs/namei.c:4863
 do_linkat+0x272/0x560 fs/namei.c:4933
 __do_sys_link fs/namei.c:4967 [inline]
 __se_sys_link fs/namei.c:4965 [inline]
 __x64_sys_link+0x82/0x90 fs/namei.c:4965
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881496a3000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 65 bytes inside of
 allocated 2048-byte region [ffff8881496a3000, ffff8881496a3800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1496a0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801a442000 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88801a442000 0000000000000000 dead000000000001
head: 0000000000000000 0000000080080008 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea000525a801 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 13597243606, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 __media_device_register+0x58/0x280 drivers/media/mc/mc-device.c:720
 vivid_create_devnodes+0x2037/0x2bf0 drivers/media/test-drivers/vivid/vivid-core.c:1749
 vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:2042 [inline]
 vivid_probe+0x5035/0x7180 drivers/media/test-drivers/vivid/vivid-core.c:2095
 platform_probe+0x148/0x1d0 drivers/base/platform.c:1404
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26a/0x9a0 drivers/base/dd.c:657
 __driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:799
 driver_probe_device+0x4f/0x430 drivers/base/dd.c:829
 __driver_attach+0x452/0x700 drivers/base/dd.c:1215
 bus_for_each_dev+0x230/0x2b0 drivers/base/bus.c:370
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881496a3700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881496a3780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881496a3800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8881496a3880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881496a3900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (266):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/14 20:41 upstream 347e9f5043c8 d8fc7335 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/08/02 08:29 upstream 0905809b38bd 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 06:30 upstream e8d780dcd957 f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/30 08:29 upstream 0919a5b3b11c f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 16:53 upstream ae388edd4a8f c4a95487 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 14:25 upstream ae388edd4a8f c4a95487 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 23:14 upstream 038d61fd6422 6654ea9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 20:51 upstream 038d61fd6422 6654ea9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 17:07 upstream 038d61fd6422 6654ea9c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 10:27 upstream b711733e89a3 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 06:26 upstream b711733e89a3 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 05:12 upstream b711733e89a3 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 03:09 upstream b711733e89a3 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 00:16 upstream b711733e89a3 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 19:39 upstream ec2df4364666 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 09:25 upstream ec2df4364666 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 07:02 upstream 302f88ff3584 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 01:26 upstream 302f88ff3584 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/08/01 17:41 upstream 89748acdf226 40127d41 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/08/01 08:24 upstream d6084bb815c4 0c075d67 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 23:57 upstream d6084bb815c4 3526e777 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 16:43 upstream 260f6f4fda93 3526e777 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 10:34 upstream 260f6f4fda93 f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 07:48 upstream 260f6f4fda93 f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 03:50 upstream 4b290aae788e f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/31 01:57 upstream 4b290aae788e f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/30 22:59 upstream 4b290aae788e f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/30 14:14 upstream 14bed9bc81ba f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/30 10:40 upstream 14bed9bc81ba f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/30 05:58 upstream 14bed9bc81ba f8f2b4da .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 23:59 upstream 86aa72182095 ba28e0a8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 22:35 upstream 86aa72182095 ba28e0a8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 21:21 upstream 86aa72182095 ba28e0a8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 19:34 upstream 86aa72182095 ba28e0a8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 12:47 upstream ced1b9e0392d c4a95487 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 10:08 upstream ced1b9e0392d c4a95487 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/28 08:15 upstream b711733e89a3 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 16:08 upstream ec2df4364666 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 13:06 upstream ec2df4364666 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 05:38 upstream 302f88ff3584 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 04:35 upstream 302f88ff3584 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 03:44 upstream 302f88ff3584 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/26 23:11 upstream 302f88ff3584 fb8f743d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/08/02 02:47 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 82af5ea7c611 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/08/01 22:55 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 82af5ea7c611 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/29 07:37 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 82af5ea7c611 c4a95487 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/07/27 17:41 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 82af5ea7c611 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
2025/06/15 18:44 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 39dfc971e42d 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: slab-out-of-bounds Write in bch2_dirent_init_name
* Struck through repros no longer work on HEAD.