syzbot
KASAN: slab-use-after-free Read in free_iova
Status:
moderation: reported on 2026/08/05 00:23
Subsystems:
iommu
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+afbcc5bb25c93186b133@syzkaller.appspotmail.com
First crash: 7d03h, last: 2d20h
Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in private_find_iova drivers/iommu/iova.c:285 [inline]
BUG: KASAN: slab-use-after-free in free_iova+0xab/0x200 drivers/iommu/iova.c:355
Read of size 8 at addr ffff888000274d60 by task syz.0.0/5327
CPU: 0 UID: 0 PID: 5327 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
private_find_iova drivers/iommu/iova.c:285 [inline]
free_iova+0xab/0x200 drivers/iommu/iova.c:355
fq_ring_free_locked+0x1ab/0x310 drivers/iommu/dma-iommu.c:155
fq_ring_free drivers/iommu/dma-iommu.c:170 [inline]
fq_flush_timeout+0x234/0x2d0 drivers/iommu/dma-iommu.c:194
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x225/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:console_flush_one_record arch/x86/include/asm/irqflags.h:-1 [inline]
RIP: 0010:console_flush_all+0x7d2/0xaf0 kernel/printk/printk.c:3343
Code: ff ff e8 81 3b 21 00 90 0f 0b 90 e9 9c fc ff ff e8 73 3b 21 00 e8 ce 5d 2d 0a 48 85 db 74 c0 e8 64 3b 21 00 fb 48 8b 5c 24 18 <48> 8b 44 24 28 42 80 3c 20 00 4d 8d 77 58 74 08 4c 89 f7 e8 e6 6d
RSP: 0018:ffffc9000f6271e0 EFLAGS: 00000283
RAX: ffffffff81a5e75c RBX: ffffc9000f627340 RCX: 0000000000100000
RDX: ffffc9000edfa000 RSI: 000000000002c5aa RDI: 000000000002c5ab
RBP: ffffc9000f6272f0 R08: ffffffff9057c237 R09: 1ffffffff20af846
R10: dffffc0000000000 R11: fffffbfff20af847 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffffffff8f471ce0
__console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
__warn_printf lib/bug.c:189 [inline]
__report_bug+0x3c5/0x570 lib/bug.c:249
report_bug_entry+0x19a/0x290 lib/bug.c:274
handle_bug+0xce/0x200 arch/x86/kernel/traps.c:431
exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:490
asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:593
RIP: 0010:debug_print_object+0x18a/0x230 lib/debugobjects.c:629
Code: f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 3d 13 56 fd 4d 8b 0f 4c 89 ef 48 8b 74 24 08 48 89 ea 44 89 e1 4d 89 f0 ff 34 24 <67> 48 0f b9 3a 48 83 c4 08 ff 05 03 b3 77 0b 48 83 c4 10 5b 41 5c
RSP: 0018:ffffc9000f6276f0 EFLAGS: 00010246
RAX: 1ffffffff17decd0 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffffff8c4bf940 RSI: ffffffff8c4bf3c0 RDI: ffffffff90632440
RBP: ffffffff8c4bf940 R08: ffff8880002684e0 R09: ffffffff8bef79e0
R10: dffffc0000000000 R11: ffffffff81b33db0 R12: 0000000000000000
R13: ffffffff90632440 R14: ffff8880002684e0 R15: ffffffff8bef6680
__debug_check_no_obj_freed lib/debugobjects.c:1171 [inline]
debug_check_no_obj_freed+0x2e3/0x450 lib/debugobjects.c:1201
slab_free_hook mm/slub.c:2608 [inline]
slab_free mm/slub.c:6377 [inline]
kfree+0x13e/0x640 mm/slub.c:6692
iommu_domain_free drivers/iommu/iommu.c:2131 [inline]
iommu_deinit_device+0x401/0x840 drivers/iommu/iommu.c:600
__iommu_group_remove_device+0x1dd/0x270 drivers/iommu/iommu.c:764
iommu_release_device drivers/iommu/iommu.c:783 [inline]
iommu_bus_notifier+0x6d/0x2c0 drivers/iommu/iommu.c:1826
notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85
blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380
bus_notify+0x143/0x180 drivers/base/bus.c:1086
device_del+0x740/0x8f0 drivers/base/core.c:3978
pci_destroy_dev drivers/pci/remove.c:46 [inline]
pci_remove_bus_device+0x12a/0x2a0 drivers/pci/remove.c:110
pci_stop_and_remove_bus_device drivers/pci/remove.c:129 [inline]
pci_stop_and_remove_bus_device_locked+0x7f/0xb0 drivers/pci/remove.c:136
remove_store+0xe5/0x150 drivers/pci/pci-sysfs.c:523
kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
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: 0033:0x7f2afa79e019
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:00007f2afb6f9fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2afaa25fa0 RCX: 00007f2afa79e019
RDX: 0000000000000001 RSI: 00002000000000c0 RDI: 0000000000000008
RBP: 00007f2afa83500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2afaa26038 R14: 00007f2afaa25fa0 R15: 00007fff4eb947c8
</TASK>
Allocated by task 1:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4584 [inline]
slab_alloc_node mm/slub.c:4917 [inline]
kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4931
alloc_iova_mem drivers/iommu/iova.c:231 [inline]
alloc_and_init_iova drivers/iommu/iova.c:474 [inline]
__insert_new_range drivers/iommu/iova.c:489 [inline]
reserve_iova+0x2b0/0x480 drivers/iommu/iova.c:544
iova_reserve_pci_windows drivers/iommu/dma-iommu.c:521 [inline]
iova_reserve_iommu_regions drivers/iommu/dma-iommu.c:563 [inline]
iommu_dma_init_domain drivers/iommu/dma-iommu.c:723 [inline]
iommu_setup_dma_ops+0xa21/0x1820 drivers/iommu/dma-iommu.c:2159
bus_iommu_probe+0x296/0x470 drivers/iommu/iommu.c:1983
iommu_device_register+0x1af/0x210 drivers/iommu/iommu.c:307
intel_iommu_init+0x6f0/0x8e0 drivers/iommu/intel/iommu.c:2662
pci_iommu_init+0x38/0x70 arch/x86/kernel/pci-dma.c:174
do_one_initcall+0x250/0x870 init/main.c:1347
do_initcall_level+0x10a/0x1a0 init/main.c:1409
do_initcalls+0x59/0xa0 init/main.c:1425
kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
kernel_init+0x1d/0x1d0 init/main.c:1548
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Freed by task 5327:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2677 [inline]
slab_free mm/slub.c:6377 [inline]
kmem_cache_free+0x182/0x650 mm/slub.c:6504
free_iova_mem drivers/iommu/iova.c:237 [inline]
put_iova_domain+0xcc/0x100 drivers/iommu/iova.c:454
iommu_put_dma_cookie+0x45c/0x560 drivers/iommu/dma-iommu.c:431
iommu_domain_free drivers/iommu/iommu.c:2131 [inline]
iommu_deinit_device+0x401/0x840 drivers/iommu/iommu.c:600
__iommu_group_remove_device+0x1dd/0x270 drivers/iommu/iommu.c:764
iommu_release_device drivers/iommu/iommu.c:783 [inline]
iommu_bus_notifier+0x6d/0x2c0 drivers/iommu/iommu.c:1826
notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85
blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380
bus_notify+0x143/0x180 drivers/base/bus.c:1086
device_del+0x740/0x8f0 drivers/base/core.c:3978
pci_destroy_dev drivers/pci/remove.c:46 [inline]
pci_remove_bus_device+0x12a/0x2a0 drivers/pci/remove.c:110
pci_stop_and_remove_bus_device drivers/pci/remove.c:129 [inline]
pci_stop_and_remove_bus_device_locked+0x7f/0xb0 drivers/pci/remove.c:136
remove_store+0xe5/0x150 drivers/pci/pci-sysfs.c:523
kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
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
The buggy address belongs to the object at ffff888000274d40
which belongs to the cache iommu_iova of size 40
The buggy address is located 32 bytes inside of
freed 40-byte region [ffff888000274d40, ffff888000274d68)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x274
flags: 0x7ff00000000000(node=0|zone=0|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 007ff00000000000 ffff888030463500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800400040 00000000f5000000 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 8498569964, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab+0x79/0x5e0 mm/slub.c:3380
new_slab mm/slub.c:3426 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
kmem_cache_alloc_noprof+0x382/0x5f0 mm/slub.c:4931
alloc_iova_mem drivers/iommu/iova.c:231 [inline]
alloc_and_init_iova drivers/iommu/iova.c:474 [inline]
__insert_new_range drivers/iommu/iova.c:489 [inline]
reserve_iova+0x2b0/0x480 drivers/iommu/iova.c:544
iova_reserve_pci_windows drivers/iommu/dma-iommu.c:521 [inline]
iova_reserve_iommu_regions drivers/iommu/dma-iommu.c:563 [inline]
iommu_dma_init_domain drivers/iommu/dma-iommu.c:723 [inline]
iommu_setup_dma_ops+0xa21/0x1820 drivers/iommu/dma-iommu.c:2159
bus_iommu_probe+0x296/0x470 drivers/iommu/iommu.c:1983
iommu_device_register+0x1af/0x210 drivers/iommu/iommu.c:307
intel_iommu_init+0x6f0/0x8e0 drivers/iommu/intel/iommu.c:2662
pci_iommu_init+0x38/0x70 arch/x86/kernel/pci-dma.c:174
do_one_initcall+0x250/0x870 init/main.c:1347
do_initcall_level+0x10a/0x1a0 init/main.c:1409
do_initcalls+0x59/0xa0 init/main.c:1425
page_owner free stack trace missing
Memory state around the buggy address:
ffff888000274c00: 00 00 00 00 00 fc fc fc 00 00 00 00 00 fc fc fc
ffff888000274c80: fa fb fb fb fb fc fc fc fa fb fb fb fb fc fc fc
>ffff888000274d00: fa fb fb fb fb fc fc fc fa fb fb fb fb fc fc fc
^
ffff888000274d80: fa fb fb fb fb fc fc fc 00 00 00 00 00 fc fc fc
ffff888000274e00: 00 00 00 00 00 fc fc fc 00 00 00 00 00 fc fc fc
==================================================================
----------------
Code disassembly (best guess), 1 bytes skipped:
0: ff ljmp (bad)
1: e8 81 3b 21 00 call 0x213b87
6: 90 nop
7: 0f 0b ud2
9: 90 nop
a: e9 9c fc ff ff jmp 0xfffffcab
f: e8 73 3b 21 00 call 0x213b87
14: e8 ce 5d 2d 0a call 0xa2d5de7
19: 48 85 db test %rbx,%rbx
1c: 74 c0 je 0xffffffde
1e: e8 64 3b 21 00 call 0x213b87
23: fb sti
24: 48 8b 5c 24 18 mov 0x18(%rsp),%rbx
* 29: 48 8b 44 24 28 mov 0x28(%rsp),%rax <-- trapping instruction
2e: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
33: 4d 8d 77 58 lea 0x58(%r15),%r14
37: 74 08 je 0x41
39: 4c 89 f7 mov %r14,%rdi
3c: e8 .byte 0xe8
3d: e6 6d out %al,$0x6d
Struck through repros no longer work on HEAD.