KASAN: slab-out-of-bounds Read in xfs_getbmap

Status: fixed on 2023/07/01 16:05
Subsystems: xfs
[Documentation on labels]
Reported-by: syzbot+c103d3808a0de5faaf80@syzkaller.appspotmail.com
Fix commit: 1bba82fe1afa xfs: fix negative array access in xfs_getbmap
First crash: 1180d, last: 1179d
Cause bisection: introduced by (bisect log) :
commit 8ee81ed581ff35882b006a5205100db0b57bf070
Author: Ye Bin <yebin10@huawei.com>
Date: Wed Apr 12 05:49:44 2023 +0000

  xfs: fix BUG_ON in xfs_getbmap()

Crash: KASAN: slab-out-of-bounds Read in xfs_getbmap (log)
Repro: C syz .config
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [xfs?] KASAN: slab-out-of-bounds Read in xfs_getbmap 5 (10) 2023/05/03 00:14
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 general protection fault in xfs_getbmap (2) 2 1 253d 253d 0/3 auto-obsoleted due to no activity on 2026/02/21 00:53
linux-5.15 general protection fault in xfs_getbmap 2 1 517d 517d 0/3 auto-obsoleted due to no activity on 2025/06/01 23:05
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2023/05/02 22:00 34m djwong@kernel.org https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git inodegc-fixes-6.4_2023-05-02 OK log
2023/05/02 21:24 21m djwong@kernel.org https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git inodegc-fixes-6.4_2023-05-01 report log

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in xfs_getbmap+0x1c06/0x1c90 fs/xfs/xfs_bmap_util.c:561
Read of size 4 at addr ffff88801872aa78 by task syz-executor294/5000

CPU: 1 PID: 5000 Comm: syz-executor294 Not tainted 6.3.0-syzkaller-12049-g58390c8ce1bd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:351 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:462
 kasan_report+0x176/0x1b0 mm/kasan/report.c:572
 xfs_getbmap+0x1c06/0x1c90 fs/xfs/xfs_bmap_util.c:561
 xfs_ioc_getbmap+0x243/0x7a0 fs/xfs/xfs_ioctl.c:1481
 xfs_file_ioctl+0xbf5/0x16a0 fs/xfs/xfs_ioctl.c:1949
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc886bade49
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 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:00007fc87f738208 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc886c3c7b8 RCX: 00007fc886bade49
RDX: 0000000020000140 RSI: 00000000c0205826 RDI: 0000000000000005
RBP: 00007fc886c3c7b0 R08: 00007fc87f738700 R09: 0000000000000000
R10: 00007fc87f738700 R11: 0000000000000246 R12: 00007fc886c3c7bc
R13: 00007ffdc483022f R14: 00007fc87f738300 R15: 0000000000022000
 </TASK>

Allocated by task 4450:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:196 [inline]
 __do_kmalloc_node mm/slab_common.c:966 [inline]
 __kmalloc_node+0xb8/0x230 mm/slab_common.c:973
 kmalloc_node include/linux/slab.h:579 [inline]
 kvmalloc_node+0x72/0x180 mm/util.c:604
 kvmalloc include/linux/slab.h:697 [inline]
 simple_xattr_alloc+0x43/0xa0 fs/xattr.c:1073
 shmem_initxattrs+0x8e/0x1e0 mm/shmem.c:3290
 security_inode_init_security+0x2df/0x3f0 security/security.c:1630
 shmem_mknod+0xba/0x1c0 mm/shmem.c:2947
 lookup_open fs/namei.c:3492 [inline]
 open_last_lookups fs/namei.c:3560 [inline]
 path_openat+0x13df/0x3170 fs/namei.c:3788
 do_filp_open+0x234/0x490 fs/namei.c:3818
 do_sys_openat2+0x13f/0x500 fs/open.c:1356
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x247/0x290 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88801872aa00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 79 bytes to the right of
 allocated 41-byte region [ffff88801872aa00, ffff88801872aa29)

The buggy address belongs to the physical page:
page:ffffea000061ca80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1872a
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000200 ffff888012441640 ffffea0000ad39c0 dead000000000002
raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 4439, tgid 4439 (S02sysctl), ts 15189537421, free_ts 15177747790
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1722
 prep_new_page mm/page_alloc.c:1729 [inline]
 get_page_from_freelist+0x321c/0x33a0 mm/page_alloc.c:3493
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4759
 alloc_slab_page+0x6a/0x160 mm/slub.c:1851
 allocate_slab mm/slub.c:1998 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2051
 ___slab_alloc+0xa85/0x10a0 mm/slub.c:3192
 __slab_alloc mm/slub.c:3291 [inline]
 __slab_alloc_node mm/slub.c:3344 [inline]
 slab_alloc_node mm/slub.c:3441 [inline]
 __kmem_cache_alloc_node+0x1b8/0x290 mm/slub.c:3490
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1057
 kmalloc include/linux/slab.h:559 [inline]
 load_elf_binary+0x1cdb/0x2830 fs/binfmt_elf.c:910
 search_binary_handler fs/exec.c:1737 [inline]
 exec_binprm fs/exec.c:1779 [inline]
 bprm_execve+0x90e/0x1740 fs/exec.c:1854
 do_execveat_common+0x580/0x720 fs/exec.c:1962
 do_execve fs/exec.c:2036 [inline]
 __do_sys_execve fs/exec.c:2112 [inline]
 __se_sys_execve fs/exec.c:2107 [inline]
 __x64_sys_execve+0x92/0xa0 fs/exec.c:2107
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1302 [inline]
 free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2555
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2696
 release_pages+0x2193/0x2470 mm/swap.c:1042
 tlb_batch_pages_flush mm/mmu_gather.c:97 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
 tlb_flush_mmu+0x100/0x210 mm/mmu_gather.c:299
 tlb_finish_mmu+0xd4/0x1f0 mm/mmu_gather.c:391
 exit_mmap+0x3da/0xaf0 mm/mmap.c:3123
 __mmput+0x115/0x3c0 kernel/fork.c:1351
 exec_mmap+0x672/0x700 fs/exec.c:1035
 begin_new_exec+0x665/0xf10 fs/exec.c:1294
 load_elf_binary+0x95d/0x2830 fs/binfmt_elf.c:1001
 search_binary_handler fs/exec.c:1737 [inline]
 exec_binprm fs/exec.c:1779 [inline]
 bprm_execve+0x90e/0x1740 fs/exec.c:1854
 do_execveat_common+0x580/0x720 fs/exec.c:1962
 do_execve fs/exec.c:2036 [inline]
 __do_sys_execve fs/exec.c:2112 [inline]
 __se_sys_execve fs/exec.c:2107 [inline]
 __x64_sys_execve+0x92/0xa0 fs/exec.c:2107
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88801872a900: 00 00 00 00 00 01 fc fc fc fc fc fc fc fc fc fc
 ffff88801872a980: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88801872aa00: 00 00 00 00 00 01 fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff88801872aa80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff88801872ab00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/05/01 18:52 upstream 58390c8ce1bd 62df2017 .config strace log report syz C [mounted in repro] ci2-upstream-fs KASAN: slab-out-of-bounds Read in xfs_getbmap
2023/05/02 07:41 upstream c8c655c34e33 62df2017 .config console log report info ci2-upstream-fs KASAN: slab-out-of-bounds Read in xfs_getbmap
2023/05/02 05:37 upstream c8c655c34e33 62df2017 .config console log report info ci2-upstream-fs KASAN: slab-out-of-bounds Read in xfs_getbmap
2023/05/01 18:49 upstream 58390c8ce1bd 62df2017 .config console log report info ci2-upstream-fs KASAN: slab-out-of-bounds Read in xfs_getbmap
2023/05/01 18:28 upstream 58390c8ce1bd 62df2017 .config console log report info ci2-upstream-fs KASAN: slab-out-of-bounds Read in xfs_getbmap
* Struck through repros no longer work on HEAD.