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KASAN: use-after-free Write in put_ucounts

Status: fixed on 2021/11/10 00:50
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+b6e65bd125a05f803d6b@syzkaller.appspotmail.com
Fix commit: 345daff2e994 ucounts: Fix race condition between alloc_ucounts and put_ucounts
First crash: 1027d, last: 1012d
▶ ▼ Discussions (7)
Title Replies (including bot) Last reply
Re: [GIT PULL] ucount fix for v5.14-rc 1 (1) 2021/08/06 03:38
[GIT PULL] ucount fix for v5.14-rc 2 (2) 2021/08/05 19:26
Re: [PATCH v1] ucounts: Fix race condition between alloc_ucounts and put_ucounts 2 (2) 2021/07/28 17:05
[PATCH v1] ucounts: Fix race condition between alloc_ucounts and put_ucounts 1 (1) 2021/07/27 15:24
Re: [syzbot] KASAN: use-after-free Write in put_ucounts 3 (3) 2021/07/25 00:32
Re: [syzbot] KASAN: use-after-free Write in put_ucounts 1 (1) 2021/07/20 16:29
[syzbot] KASAN: use-after-free Write in put_ucounts 0 (1) 2021/07/17 06:22
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Write in put_ucounts (2) kernel 1 837d 833d 0/26 closed as dup on 2022/01/17 08:21

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: use-after-free in atomic_dec_and_test include/asm-generic/atomic-instrumented.h:542 [inline]
BUG: KASAN: use-after-free in put_ucounts+0x1c/0x150 kernel/ucount.c:196
Write of size 4 at addr ffff88801d11061c by task systemd-udevd/4874

CPU: 1 PID: 4874 Comm: systemd-udevd Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_dec_and_test include/asm-generic/atomic-instrumented.h:542 [inline]
 put_ucounts+0x1c/0x150 kernel/ucount.c:196
 put_cred_rcu+0x27a/0x520 kernel/cred.c:124
 rcu_do_batch kernel/rcu/tree.c:2550 [inline]
 rcu_core+0x7ab/0x1380 kernel/rcu/tree.c:2785
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:rmqueue mm/page_alloc.c:3742 [inline]
RIP: 0010:get_page_from_freelist+0x8c1/0x2f80 mm/page_alloc.c:4163
Code: e8 a4 f8 a8 ff 48 83 7c 24 60 00 0f 85 8e 12 00 00 9c 58 f6 c4 02 0f 85 f6 17 00 00 48 83 7c 24 60 00 74 01 fb 48 8b 44 24 28 <49> 8d 9e b8 05 00 00 48 85 c0 0f 84 66 0f 00 00 48 c1 e8 03 42 80
RSP: 0018:ffffc9000a6bf4b8 EFLAGS: 00000206
RAX: ffffea000143bb40 RBX: 0000000000000001 RCX: 1ffffffff1f9acc2
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880b9d4d660 R08: 0000000000000001 R09: ffffffff8fccf8b7
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8880b9d4d688
R13: dffffc0000000000 R14: ffff88813fffb700 R15: 0000000000000000
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5388
 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2244
 __pte_alloc_one include/asm-generic/pgalloc.h:63 [inline]
 pte_alloc_one+0x16/0x230 arch/x86/mm/pgtable.c:33
 __pte_alloc+0x1f/0x2d0 mm/memory.c:439
 copy_pte_range mm/memory.c:1021 [inline]
 copy_pmd_range mm/memory.c:1156 [inline]
 copy_pud_range mm/memory.c:1193 [inline]
 copy_p4d_range mm/memory.c:1217 [inline]
 copy_page_range+0x1789/0x4420 mm/memory.c:1290
 dup_mmap kernel/fork.c:598 [inline]
 dup_mm+0x9e7/0x1380 kernel/fork.c:1379
 copy_mm kernel/fork.c:1431 [inline]
 copy_process+0x71ec/0x74d0 kernel/fork.c:2119
 kernel_clone+0xe7/0xac0 kernel/fork.c:2509
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2626
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f52851df38b
Code: db 45 85 f6 0f 85 95 01 00 00 64 4c 8b 04 25 10 00 00 00 31 d2 4d 8d 90 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 de 00 00 00 85 c0 41 89 c5 0f 85 e5 00 00
RSP: 002b:00007fff70f344c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fff70f344c0 RCX: 00007f52851df38b
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007fff70f34510 R08: 00007f52863908c0 R09: 0000000000000210
R10: 00007f5286390b90 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000020 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 8480:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 alloc_ucounts+0x23d/0x5b0 kernel/ucount.c:169
 set_cred_ucounts+0x171/0x3a0 kernel/cred.c:684
 copy_creds+0x70e/0xb60 kernel/cred.c:375
 copy_process+0x13c5/0x74d0 kernel/fork.c:1992
 kernel_clone+0xe7/0xac0 kernel/fork.c:2509
 __do_sys_clone+0xc8/0x110 kernel/fork.c:2626
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 4874:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1625 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1650
 slab_free mm/slub.c:3210 [inline]
 kfree+0xeb/0x650 mm/slub.c:4262
 put_ucounts kernel/ucount.c:200 [inline]
 put_ucounts+0x117/0x150 kernel/ucount.c:192
 dec_pid_namespaces kernel/pid_namespace.c:67 [inline]
 delayed_free_pidns+0x3f/0x120 kernel/pid_namespace.c:127
 rcu_do_batch kernel/rcu/tree.c:2550 [inline]
 rcu_core+0x7ab/0x1380 kernel/rcu/tree.c:2785
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 insert_work+0x48/0x370 kernel/workqueue.c:1332
 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
 queue_work_on+0xee/0x110 kernel/workqueue.c:1525
 queue_work include/linux/workqueue.h:507 [inline]
 call_usermodehelper_exec+0x1f0/0x4c0 kernel/umh.c:435
 kobject_uevent_env+0xf8f/0x1650 lib/kobject_uevent.c:618
 kobject_synth_uevent+0x701/0x850 lib/kobject_uevent.c:208
 uevent_store+0x20/0x50 drivers/base/core.c:2370
 dev_attr_store+0x50/0x80 drivers/base/core.c:2071
 sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write+0x426/0x650 fs/read_write.c:518
 vfs_write+0x75a/0xa40 fs/read_write.c:605
 ksys_write+0x12d/0x250 fs/read_write.c:658
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 insert_work+0x48/0x370 kernel/workqueue.c:1332
 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
 queue_work_on+0xee/0x110 kernel/workqueue.c:1525
 queue_work include/linux/workqueue.h:507 [inline]
 call_usermodehelper_exec+0x1f0/0x4c0 kernel/umh.c:435
 kobject_uevent_env+0xf8f/0x1650 lib/kobject_uevent.c:618
 kobject_synth_uevent+0x701/0x850 lib/kobject_uevent.c:208
 uevent_store+0x42/0x90 drivers/base/bus.c:581
 drv_attr_store+0x6d/0xa0 drivers/base/bus.c:77
 sysfs_kf_write+0x110/0x160 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write+0x426/0x650 fs/read_write.c:518
 vfs_write+0x75a/0xa40 fs/read_write.c:605
 ksys_write+0x12d/0x250 fs/read_write.c:658
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801d110600
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 28 bytes inside of
 192-byte region [ffff88801d110600, ffff88801d1106c0)
The buggy address belongs to the page:
page:ffffea0000744400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1d110
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00005e3480 0000000200000002 ffff888010841a00
raw: 0000000000000000 0000000000100010 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 1, ts 8484287209, free_ts 8471198798
 prep_new_page mm/page_alloc.c:2433 [inline]
 get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4166
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5388
 alloc_page_interleave+0x1e/0x200 mm/mempolicy.c:2119
 alloc_pages+0x238/0x2a0 mm/mempolicy.c:2242
 alloc_slab_page mm/slub.c:1688 [inline]
 allocate_slab+0x32e/0x4b0 mm/slub.c:1828
 new_slab mm/slub.c:1891 [inline]
 new_slab_objects mm/slub.c:2637 [inline]
 ___slab_alloc+0x4ba/0x820 mm/slub.c:2800
 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2840
 slab_alloc_node mm/slub.c:2922 [inline]
 slab_alloc mm/slub.c:2964 [inline]
 kmem_cache_alloc_trace+0x30f/0x3c0 mm/slub.c:2981
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 call_usermodehelper_setup+0x97/0x340 kernel/umh.c:365
 kobject_uevent_env+0xf73/0x1650 lib/kobject_uevent.c:614
 driver_register+0x2db/0x3a0 drivers/base/driver.c:179
 init_tis+0x11a/0x1c5 drivers/char/tpm/tpm_tis.c:393
 do_one_initcall+0x103/0x650 init/main.c:1282
 do_initcall_level init/main.c:1355 [inline]
 do_initcalls init/main.c:1371 [inline]
 do_basic_setup init/main.c:1391 [inline]
 kernel_init_freeable+0x6b8/0x741 init/main.c:1593
 kernel_init+0x1a/0x1d0 init/main.c:1485
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1343 [inline]
 free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1394
 free_unref_page_prepare mm/page_alloc.c:3329 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3408
 __vunmap+0x783/0xb70 mm/vmalloc.c:2587
 free_work+0x58/0x70 mm/vmalloc.c:82
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff88801d110500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801d110580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88801d110600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88801d110680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88801d110700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/07/19 13:59 upstream 2734d6c1b1a0 e6a17580 .config console log report info ci-upstream-kasan-gce KASAN: use-after-free Write in put_ucounts
2021/07/08 22:00 upstream 3dbdb38e2869 1b20171a .config console log report info ci-upstream-kasan-gce-386 KASAN: use-after-free Write in put_ucounts
2021/07/04 13:25 upstream 3dbdb38e2869 55aa55c2 .config console log report info ci-upstream-kasan-gce-386 KASAN: use-after-free Write in put_ucounts
* Struck through repros no longer work on HEAD.