syzbot


KASAN: slab-use-after-free Read in lockref_get_not_dead

Status: moderation: reported on 2024/03/19 05:42
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+cbe4b96e1194b0e34db6@syzkaller.appspotmail.com
First crash: 30d, last: 30d

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __lock_acquire+0x2dd6/0x3b30 kernel/locking/lockdep.c:5005
Read of size 8 at addr ffff888042f3d250 by task syz-executor.4/19792

CPU: 1 PID: 19792 Comm: syz-executor.4 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 __lock_acquire+0x2dd6/0x3b30 kernel/locking/lockdep.c:5005
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x540 kernel/locking/lockdep.c:5719
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 lockref_get_not_dead+0x18/0x80 lib/lockref.c:184
 get_stashed_dentry fs/libfs.c:1998 [inline]
 path_from_stashed+0x160/0xe00 fs/libfs.c:2092
 ns_get_path_cb fs/nsfs.c:59 [inline]
 ns_get_path+0x5f/0x80 fs/nsfs.c:82
 proc_ns_get_link+0x122/0x270 fs/proc/namespaces.c:61
 pick_link fs/namei.c:1808 [inline]
 step_into+0x1aed/0x2230 fs/namei.c:1874
 open_last_lookups fs/namei.c:3589 [inline]
 path_openat+0x448/0x2990 fs/namei.c:3796
 do_filp_open+0x1dc/0x430 fs/namei.c:3826
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1432
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7fdcad87c9a0
Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 09 82 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 5c 82 02 00 8b 44
RSP: 002b:00007fdcae698ff0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdcad87c9a0
RDX: 0000000000000000 RSI: 00007fdcad8c9265 RDI: 00000000ffffff9c
RBP: 00007fdcad8c9265 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 000000000000000b R14: 00007fdcad9ac050 R15: 00007ffc40f09798
 </TASK>

Allocated by task 19791:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:312 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:338
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3798 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmem_cache_alloc_lru+0x142/0x6f0 mm/slub.c:3864
 __d_alloc+0x31/0xaa0 fs/dcache.c:1624
 prepare_anon_dentry fs/libfs.c:2032 [inline]
 path_from_stashed+0x6eb/0xe00 fs/libfs.c:2099
 ns_get_path_cb fs/nsfs.c:59 [inline]
 ns_get_path+0x5f/0x80 fs/nsfs.c:82
 proc_ns_get_link+0x122/0x270 fs/proc/namespaces.c:61
 pick_link fs/namei.c:1808 [inline]
 step_into+0x1aed/0x2230 fs/namei.c:1874
 open_last_lookups fs/namei.c:3589 [inline]
 path_openat+0x448/0x2990 fs/namei.c:3796
 do_filp_open+0x1dc/0x430 fs/namei.c:3826
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1432
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Freed by task 18096:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:240 [inline]
 __kasan_slab_free+0x11d/0x1a0 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2106 [inline]
 slab_free mm/slub.c:4280 [inline]
 kmem_cache_free+0x12e/0x360 mm/slub.c:4344
 rcu_do_batch kernel/rcu/tree.c:2196 [inline]
 rcu_core+0x828/0x16b0 kernel/rcu/tree.c:2471
 __do_softirq+0x218/0x8de kernel/softirq.c:554

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xba/0xd0 mm/kasan/generic.c:541
 __call_rcu_common.constprop.0+0x9a/0x790 kernel/rcu/tree.c:2734
 dentry_free+0xc2/0x160 fs/dcache.c:376
 __dentry_kill+0x498/0x600 fs/dcache.c:622
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:845
 dput+0x1f/0x30 fs/dcache.c:835
 __fput+0x3bc/0xb80 fs/file_table.c:430
 __fput_sync+0x47/0x50 fs/file_table.c:507
 __do_sys_close fs/open.c:1556 [inline]
 __se_sys_close fs/open.c:1541 [inline]
 __x64_sys_close+0x86/0x100 fs/open.c:1541
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

The buggy address belongs to the object at ffff888042f3d1a0
 which belongs to the cache dentry of size 312
The buggy address is located 176 bytes inside of
 freed 312-byte region [ffff888042f3d1a0, ffff888042f3d2d8)

The buggy address belongs to the physical page:
page:ffffea00010bcf00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x42f3c
head:ffffea00010bcf00 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888066791e01
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888015ef03c0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000150015 00000001ffffffff ffff888066791e01
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Reclaimable, gfp_mask 0x1d20d0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_RECLAIMABLE), pid 19791, tgid 19790 (syz-executor.4), ts 1264577584789, free_ts 1160902656352
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1533
 prep_new_page mm/page_alloc.c:1540 [inline]
 get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3311
 __alloc_pages+0x22b/0x2410 mm/page_alloc.c:4569
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page mm/slub.c:2175 [inline]
 allocate_slab mm/slub.c:2338 [inline]
 new_slab+0xcc/0x3a0 mm/slub.c:2391
 ___slab_alloc+0x66d/0x1790 mm/slub.c:3525
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3610
 __slab_alloc_node mm/slub.c:3663 [inline]
 slab_alloc_node mm/slub.c:3835 [inline]
 kmem_cache_alloc_lru+0x379/0x6f0 mm/slub.c:3864
 __d_alloc+0x31/0xaa0 fs/dcache.c:1624
 prepare_anon_dentry fs/libfs.c:2032 [inline]
 path_from_stashed+0x6eb/0xe00 fs/libfs.c:2099
 ns_get_path_cb fs/nsfs.c:59 [inline]
 ns_get_path+0x5f/0x80 fs/nsfs.c:82
 proc_ns_get_link+0x122/0x270 fs/proc/namespaces.c:61
 pick_link fs/namei.c:1808 [inline]
 step_into+0x1aed/0x2230 fs/namei.c:1874
 open_last_lookups fs/namei.c:3589 [inline]
 path_openat+0x448/0x2990 fs/namei.c:3796
 do_filp_open+0x1dc/0x430 fs/namei.c:3826
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1432
page last free pid 14503 tgid 14503 stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1140 [inline]
 free_unref_page_prepare+0x527/0xb10 mm/page_alloc.c:2346
 free_unref_page+0x33/0x3c0 mm/page_alloc.c:2486
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4e/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x192/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:322
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3798 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmem_cache_alloc+0x136/0x320 mm/slub.c:3852
 mt_alloc_one lib/maple_tree.c:162 [inline]
 mas_alloc_nodes+0x176/0x860 lib/maple_tree.c:1242
 mas_node_count_gfp+0x105/0x130 lib/maple_tree.c:1322
 mas_preallocate+0x3bb/0x1020 lib/maple_tree.c:5558
 vma_iter_prealloc mm/internal.h:1147 [inline]
 vma_expand+0x76d/0x13c0 mm/mmap.c:658
 mmap_region+0x17d4/0x2aa0 mm/mmap.c:2800
 do_mmap+0x8ae/0xf10 mm/mmap.c:1387
 vm_mmap_pgoff+0x1ab/0x3c0 mm/util.c:573
 ksys_mmap_pgoff+0x425/0x5b0 mm/mmap.c:1433
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:79 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:79
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83

Memory state around the buggy address:
 ffff888042f3d100: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff888042f3d180: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
>ffff888042f3d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888042f3d280: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
 ffff888042f3d300: fc fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/03/15 05:35 upstream fe46a7dd189e d615901c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in lockref_get_not_dead
* Struck through repros no longer work on HEAD.