* [syzbot] [net?] KASAN: use-after-free Read in filemap_map_pages
@ 2026-06-01 11:47 syzbot
2026-08-15 12:51 ` [syzbot] [bridge?] " syzbot
2026-08-16 6:43 ` Forwarded: " syzbot
0 siblings, 2 replies; 5+ messages in thread
From: syzbot @ 2026-06-01 11:47 UTC (permalink / raw)
To: davem, edumazet, horms, kuba, linux-kernel, netdev, pabeni,
syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: d60ec36cab33 Merge tag 'mm-hotfixes-stable-2026-05-25-16-2..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124501ec580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8d24a1331e060dda
dashboard link: https://syzkaller.appspot.com/bug?extid=b72767277f29b6407083
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: i386
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/864236422e21/disk-d60ec36c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/858219f0a900/vmlinux-d60ec36c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/809d091c238e/bzImage-d60ec36c.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b72767277f29b6407083@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: use-after-free in ptep_get include/linux/pgtable.h:461 [inline]
BUG: KASAN: use-after-free in filemap_map_order0_folio mm/filemap.c:3856 [inline]
BUG: KASAN: use-after-free in filemap_map_pages+0xc7a/0x2100 mm/filemap.c:3932
Read of size 8 at addr ffff88807bed6d50 by task syz.1.7707/30545
CPU: 1 UID: 0 PID: 30545 Comm: syz.1.7707 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
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
ptep_get include/linux/pgtable.h:461 [inline]
filemap_map_order0_folio mm/filemap.c:3856 [inline]
filemap_map_pages+0xc7a/0x2100 mm/filemap.c:3932
do_fault_around mm/memory.c:5867 [inline]
do_read_fault mm/memory.c:5900 [inline]
do_fault mm/memory.c:6043 [inline]
do_pte_missing+0x1f38/0x33f0 mm/memory.c:4566
handle_pte_fault mm/memory.c:6427 [inline]
__handle_mm_fault mm/memory.c:6565 [inline]
handle_mm_fault+0x1bf2/0x3170 mm/memory.c:6734
do_user_addr_fault+0x75b/0x1340 arch/x86/mm/fault.c:1385
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:rep_movs_alternative+0x30/0x90 arch/x86/lib/copy_user_64.S:60
Code: 83 f9 08 73 25 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 c3 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 <48> 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08
RSP: 0000:ffffc9000cb978b8 EFLAGS: 00050206
RAX: 00007ffffffff001 RBX: 000000000000001c RCX: 000000000000001c
RDX: 0000000000000001 RSI: 00000000800bcae0 RDI: ffffc9000cb97940
RBP: ffffc9000cb979d0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52001972f2b R12: dffffc0000000000
R13: ffffc9000cb97c80 R14: ffffc9000cb97940 R15: 00000000800bcae0
copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
_inline_copy_from_user include/linux/uaccess.h:185 [inline]
_copy_from_user+0x7a/0xb0 lib/usercopy.c:18
copy_from_user include/linux/uaccess.h:223 [inline]
get_compat_msghdr+0xb3/0x4c0 net/compat.c:91
recvmsg_copy_msghdr net/socket.c:2882 [inline]
___sys_recvmsg+0x1dd/0x590 net/socket.c:2956
do_recvmmsg+0x3a5/0x800 net/socket.c:3047
__sys_recvmmsg+0x1a5/0x290 net/socket.c:3129
__do_compat_sys_recvmmsg_time32 net/compat.c:418 [inline]
__se_compat_sys_recvmmsg_time32 net/compat.c:414 [inline]
__ia32_compat_sys_recvmmsg_time32+0xbf/0xe0 net/compat.c:414
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
__do_fast_syscall_32+0x229/0x6e0 arch/x86/entry/syscall_32.c:307
do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7fa501c
Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8
RSP: 002b:00000000f544550c EFLAGS: 00000206 ORIG_RAX: 0000000000000151
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00000000800000c0
RDX: 0000000000010106 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x121f pfn:0x7bed6
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0000fea188 ffffea0002346808 0000000000000000
raw: 000000000000121f 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x140cc2(GFP_HIGHUSER|__GFP_COMP), pid 29415, tgid 29414 (syz.1.7355), ts 1634224509357, free_ts 1634614223058
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
prep_new_page mm/page_alloc.c:1861 [inline]
get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2591
filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1014
filemap_create_folio mm/filemap.c:2612 [inline]
filemap_get_pages+0x819/0x1ef0 mm/filemap.c:2702
filemap_read+0x447/0x1230 mm/filemap.c:2806
__kernel_read+0x504/0x9b0 fs/read_write.c:532
integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
ima_calc_file_hash+0x446/0x860 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x51d/0x9c0 security/integrity/ima/ima_api.c:300
process_measurement+0x12cd/0x1c80 security/integrity/ima/ima_main.c:425
ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
security_file_post_open+0xb3/0x260 security/security.c:2755
page last free pid 29415 tgid 29414 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1397 [inline]
free_unref_folios+0xd9f/0x14c0 mm/page_alloc.c:2999
folios_put_refs+0x9ff/0xb40 mm/swap.c:1008
folio_batch_release include/linux/folio_batch.h:101 [inline]
truncate_inode_pages_range+0x3dd/0xe30 mm/truncate.c:408
evict+0x631/0xb10 fs/inode.c:843
__dentry_kill+0x1a2/0x690 fs/dcache.c:718
shrink_kill+0xa9/0x2c0 fs/dcache.c:1195
shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1222
shrink_dcache_tree+0xe9/0x5d0 fs/dcache.c:-1
do_one_tree fs/dcache.c:1721 [inline]
shrink_dcache_for_umount+0xa8/0x1f0 fs/dcache.c:1738
generic_shutdown_super+0x6f/0x2d0 fs/super.c:624
kill_anon_super+0x3b/0x70 fs/super.c:1292
deactivate_locked_super+0xbc/0x130 fs/super.c:476
cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x70f/0x22c0 kernel/exit.c:976
do_group_exit+0x21b/0x2d0 kernel/exit.c:1119
Memory state around the buggy address:
ffff88807bed6c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88807bed6c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88807bed6d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88807bed6d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88807bed6e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
----------------
Code disassembly (best guess):
0: 83 f9 08 cmp $0x8,%ecx
3: 73 25 jae 0x2a
5: 85 c9 test %ecx,%ecx
7: 74 0f je 0x18
9: 8a 06 mov (%rsi),%al
b: 88 07 mov %al,(%rdi)
d: 48 ff c7 inc %rdi
10: 48 ff c6 inc %rsi
13: 48 ff c9 dec %rcx
16: 75 f1 jne 0x9
18: c3 ret
19: cc int3
1a: cc int3
1b: cc int3
1c: cc int3
1d: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
24: 00 00 00
27: 0f 1f 00 nopl (%rax)
* 2a: 48 8b 06 mov (%rsi),%rax <-- trapping instruction
2d: 48 89 07 mov %rax,(%rdi)
30: 48 83 c6 08 add $0x8,%rsi
34: 48 83 c7 08 add $0x8,%rdi
38: 83 e9 08 sub $0x8,%ecx
3b: 74 db je 0x18
3d: 83 f9 08 cmp $0x8,%ecx
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [bridge?] KASAN: use-after-free Read in filemap_map_pages
2026-06-01 11:47 [syzbot] [net?] KASAN: use-after-free Read in filemap_map_pages syzbot
@ 2026-08-15 12:51 ` syzbot
2026-08-16 2:17 ` Hillf Danton
2026-08-16 6:43 ` Forwarded: " syzbot
1 sibling, 1 reply; 5+ messages in thread
From: syzbot @ 2026-08-15 12:51 UTC (permalink / raw)
To: bridge, davem, edumazet, horms, idosch, kuba, linux-kernel,
netdev, pabeni, razor, syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: 15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11cfe279580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=b72767277f29b6407083
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15cfe279580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b72767277f29b6407083@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: use-after-free in ptep_get include/linux/pgtable.h:495 [inline]
BUG: KASAN: use-after-free in filemap_map_folio_range mm/filemap.c:3820 [inline]
BUG: KASAN: use-after-free in filemap_map_pages+0x1b75/0x1f80 mm/filemap.c:3955
Read of size 8 at addr ffff88803f851a00 by task syz-executor403/6035
CPU: 2 UID: 0 PID: 6035 Comm: syz-executor403 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:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
ptep_get include/linux/pgtable.h:495 [inline]
filemap_map_folio_range mm/filemap.c:3820 [inline]
filemap_map_pages+0x1b75/0x1f80 mm/filemap.c:3955
do_fault_around mm/memory.c:5818 [inline]
do_read_fault mm/memory.c:5851 [inline]
do_fault+0x985/0x1750 mm/memory.c:5994
do_pte_missing mm/memory.c:4566 [inline]
handle_pte_fault mm/memory.c:6379 [inline]
__handle_mm_fault+0x187d/0x2a00 mm/memory.c:6517
handle_mm_fault+0x37b/0xa30 mm/memory.c:6686
do_user_addr_fault+0x74c/0x12f0 arch/x86/mm/fault.c:1394
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0010:fault_in_readable+0xde/0x190 mm/gup.c:2161
Code: 68 46 ae ff 4c 89 f0 48 85 c0 0f 85 bf 00 00 00 e8 77 4c ae ff 0f 01 cb 0f ae e8 4c 89 fb 4d 85 ff 75 31 eb 48 e8 62 4c ae ff <44> 8a 33 e8 5a 4c ae ff 48 81 c3 00 10 00 00 31 ff 48 81 e3 00 f0
RSP: 0018:ffffc90003a87af8 EFLAGS: 00050293
RAX: 0000000000000000 RBX: 00007fe62c200000 RCX: ffffffff825c2758
RDX: ffff888033b84a80 RSI: ffffffff825c271e RDI: ffff888033b84a80
RBP: 00007fe62c200001 R08: 0000000000000006 R09: 00007fe62c200001
R10: 00007fe62c200000 R11: 0000000000000000 R12: 0000000000000001
R13: 1ffff92000750f60 R14: 0000000000000000 R15: 00007fe62c200000
fault_in_iov_iter_readable+0x101/0x2c0 lib/iov_iter.c:106
generic_perform_write+0x863/0xa40 mm/filemap.c:4413
shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3424
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_pwrite64 fs/read_write.c:794 [inline]
__do_sys_pwrite64 fs/read_write.c:802 [inline]
__se_sys_pwrite64 fs/read_write.c:799 [inline]
__x64_sys_pwrite64+0x1eb/0x250 fs/read_write.c:799
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe62c7fce5e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fe62b9fe1a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fe62b9fe6c0 RCX: 00007fe62c7fce5e
RDX: 0000000000000001 RSI: 00007fe62c200000 RDI: 0000000000000003
RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000000 R14: 00007ffdde346d90 R15: 00007ffdde346e78
</TASK>
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888000000000 pfn:0x3f851
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: ffff888000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x440dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_COMP), pid 6004, tgid 6004 (cmp), ts 79653237963, free_ts 79740307238
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
alloc_pages_noprof+0x1a/0x160 mm/mempolicy.c:2581
pagetable_alloc_noprof include/linux/mm.h:3685 [inline]
pmd_alloc_one_noprof include/asm-generic/pgalloc.h:143 [inline]
__pmd_alloc+0x3b/0x950 mm/memory.c:6772
pmd_alloc include/linux/mm.h:3601 [inline]
__handle_mm_fault+0xa9c/0x2a00 mm/memory.c:6469
handle_mm_fault+0x37b/0xa30 mm/memory.c:6686
do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1343
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
page last free pid 6002 tgid 6002 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
__pagetable_free include/linux/mm.h:3695 [inline]
pagetable_free include/linux/mm.h:3719 [inline]
pagetable_dtor_free include/linux/mm.h:3818 [inline]
__tlb_remove_table include/asm-generic/tlb.h:221 [inline]
__tlb_remove_table_free mm/mmu_gather.c:228 [inline]
tlb_remove_table_rcu+0x2cf/0x380 mm/mmu_gather.c:291
rcu_do_batch kernel/rcu/tree.c:2645 [inline]
rcu_core+0x5a2/0x10d0 kernel/rcu/tree.c:2897
handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x162/0x210 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+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
Memory state around the buggy address:
ffff88803f851900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88803f851980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803f851a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88803f851a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88803f851b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
----------------
Code disassembly (best guess):
0: 68 46 ae ff 4c push $0x4cffae46
5: 89 f0 mov %esi,%eax
7: 48 85 c0 test %rax,%rax
a: 0f 85 bf 00 00 00 jne 0xcf
10: e8 77 4c ae ff call 0xffae4c8c
15: 0f 01 cb stac
18: 0f ae e8 lfence
1b: 4c 89 fb mov %r15,%rbx
1e: 4d 85 ff test %r15,%r15
21: 75 31 jne 0x54
23: eb 48 jmp 0x6d
25: e8 62 4c ae ff call 0xffae4c8c
* 2a: 44 8a 33 mov (%rbx),%r14b <-- trapping instruction
2d: e8 5a 4c ae ff call 0xffae4c8c
32: 48 81 c3 00 10 00 00 add $0x1000,%rbx
39: 31 ff xor %edi,%edi
3b: 48 rex.W
3c: 81 .byte 0x81
3d: e3 00 jrcxz 0x3f
3f: f0 lock
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [bridge?] KASAN: use-after-free Read in filemap_map_pages
2026-08-15 12:51 ` [syzbot] [bridge?] " syzbot
@ 2026-08-16 2:17 ` Hillf Danton
2026-08-16 2:34 ` syzbot
0 siblings, 1 reply; 5+ messages in thread
From: Hillf Danton @ 2026-08-16 2:17 UTC (permalink / raw)
To: syzbot; +Cc: linux-kernel, syzkaller-bugs
> Date: Sat, 15 Aug 2026 05:51:23 -0700 [thread overview]
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: 15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11cfe279580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
> dashboard link: https://syzkaller.appspot.com/bug?extid=b72767277f29b6407083
> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15cfe279580000
#syz test
--- x/mm/mmu_gather.c
+++ y/mm/mmu_gather.c
@@ -358,7 +358,7 @@ static inline void __tlb_remove_table_on
#else
static inline void __tlb_remove_table_one(void *table)
{
- tlb_remove_table_sync_rcu();
+ tlb_remove_table_sync_one();
__tlb_remove_table(table);
}
#endif /* CONFIG_PT_RECLAIM */
--
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [bridge?] KASAN: use-after-free Read in filemap_map_pages
2026-08-16 2:17 ` Hillf Danton
@ 2026-08-16 2:34 ` syzbot
0 siblings, 0 replies; 5+ messages in thread
From: syzbot @ 2026-08-16 2:34 UTC (permalink / raw)
To: hdanton, linux-kernel, syzkaller-bugs
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-out-of-bounds Read in filemap_map_pages
==================================================================
BUG: KASAN: slab-out-of-bounds in ptep_get include/linux/pgtable.h:495 [inline]
BUG: KASAN: slab-out-of-bounds in filemap_map_folio_range mm/filemap.c:3820 [inline]
BUG: KASAN: slab-out-of-bounds in filemap_map_pages+0x1b75/0x1f80 mm/filemap.c:3955
Read of size 8 at addr ffff88803cb81a60 by task syz-executor275/6045
CPU: 0 UID: 0 PID: 6045 Comm: syz-executor275 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:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
ptep_get include/linux/pgtable.h:495 [inline]
filemap_map_folio_range mm/filemap.c:3820 [inline]
filemap_map_pages+0x1b75/0x1f80 mm/filemap.c:3955
do_fault_around mm/memory.c:5818 [inline]
do_read_fault mm/memory.c:5851 [inline]
do_fault+0x985/0x1750 mm/memory.c:5994
do_pte_missing mm/memory.c:4566 [inline]
handle_pte_fault mm/memory.c:6379 [inline]
__handle_mm_fault+0x187d/0x2a00 mm/memory.c:6517
handle_mm_fault+0x37b/0xa30 mm/memory.c:6686
do_user_addr_fault+0x74c/0x12f0 arch/x86/mm/fault.c:1394
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0010:fault_in_readable+0xde/0x190 mm/gup.c:2161
Code: 68 46 ae ff 4c 89 f0 48 85 c0 0f 85 bf 00 00 00 e8 77 4c ae ff 0f 01 cb 0f ae e8 4c 89 fb 4d 85 ff 75 31 eb 48 e8 62 4c ae ff <44> 8a 33 e8 5a 4c ae ff 48 81 c3 00 10 00 00 31 ff 48 81 e3 00 f0
RSP: 0018:ffffc900030d7af8 EFLAGS: 00050293
RAX: 0000000000000000 RBX: 00007fb9fe400000 RCX: ffffffff825c2758
RDX: ffff88802a614a80 RSI: ffffffff825c271e RDI: ffff88802a614a80
RBP: 00007fb9fe400001 R08: 0000000000000006 R09: 00007fb9fe400001
R10: 00007fb9fe400000 R11: 0000000000000000 R12: 0000000000000001
R13: 1ffff9200061af60 R14: 0000000000000000 R15: 00007fb9fe400000
fault_in_iov_iter_readable+0x101/0x2c0 lib/iov_iter.c:106
generic_perform_write+0x863/0xa40 mm/filemap.c:4413
shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3424
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x6ac/0x1050 fs/read_write.c:687
ksys_pwrite64 fs/read_write.c:794 [inline]
__do_sys_pwrite64 fs/read_write.c:802 [inline]
__se_sys_pwrite64 fs/read_write.c:799 [inline]
__x64_sys_pwrite64+0x1eb/0x250 fs/read_write.c:799
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb9fe9f8e5e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fb9fdbfe1a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fb9fdbfe6c0 RCX: 00007fb9fe9f8e5e
RDX: 0000000000000001 RSI: 00007fb9fe400000 RDI: 0000000000000003
RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000000 R14: 00007fff5b6bda40 R15: 00007fff5b6bdb28
</TASK>
Allocated by task 5144:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__do_kmalloc_node mm/slub.c:5334 [inline]
__kvmalloc_node_noprof+0x34f/0x970 mm/slub.c:6905
simple_xattr_alloc+0x6c/0xd0 fs/xattr.c:1271
class_simple_xattr_constructor include/linux/xattr.h:166 [inline]
simple_xattr_set+0xa8/0x3ca0 fs/xattr.c:1438
shmem_xattr_handler_set+0x326/0x3c0 mm/shmem.c:4266
__vfs_setxattr+0x175/0x1e0 fs/xattr.c:223
__vfs_setxattr_noperm+0x127/0x660 fs/xattr.c:257
__vfs_setxattr_locked+0x127/0x2b0 fs/xattr.c:318
vfs_setxattr+0x14a/0x390 fs/xattr.c:344
do_setxattr+0x145/0x180 fs/xattr.c:662
filename_setxattr+0x167/0x1d0 fs/xattr.c:690
path_setxattrat+0x1ff/0x3b0 fs/xattr.c:734
__do_sys_lsetxattr fs/xattr.c:775 [inline]
__se_sys_lsetxattr fs/xattr.c:771 [inline]
__x64_sys_lsetxattr+0xc9/0x140 fs/xattr.c:771
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88803cb81a00
which belongs to the cache kmalloc-cg-128 of size 128
The buggy address is located 96 bytes inside of
allocated 98-byte region [ffff88803cb81a00, ffff88803cb81a62)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803cb81f00 pfn:0x3cb81
flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000200 ffff88801c049b80 ffffea000161cb90 ffffea0000b6dbd0
raw: ffff88803cb81f00 000000080010000f 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 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5144, tgid 5144 (udevd), ts 32535993040, free_ts 32521083899
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab mm/slub.c:3380 [inline]
new_slab+0xa2/0x640 mm/slub.c:3426
refill_objects+0xe3/0x410 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kvmalloc_node_noprof+0x793/0x970 mm/slub.c:6905
simple_xattr_alloc+0x6c/0xd0 fs/xattr.c:1271
class_simple_xattr_constructor include/linux/xattr.h:166 [inline]
simple_xattr_set+0xa8/0x3ca0 fs/xattr.c:1438
shmem_xattr_handler_set+0x326/0x3c0 mm/shmem.c:4266
__vfs_setxattr+0x175/0x1e0 fs/xattr.c:223
__vfs_setxattr_noperm+0x127/0x660 fs/xattr.c:257
__vfs_setxattr_locked+0x127/0x2b0 fs/xattr.c:318
vfs_setxattr+0x14a/0x390 fs/xattr.c:344
do_setxattr+0x145/0x180 fs/xattr.c:662
filename_setxattr+0x167/0x1d0 fs/xattr.c:690
page last free pid 5152 tgid 5152 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
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]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kmalloc_noprof+0x2bf/0x820 mm/slub.c:5359
_kmalloc_noprof include/linux/slab.h:992 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
tomoyo_encode2+0xfb/0x3c0 security/tomoyo/realpath.c:45
tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80
tomoyo_realpath_from_path+0x18c/0x690 security/tomoyo/realpath.c:283
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x276/0x460 security/tomoyo/file.c:827
security_inode_getattr+0x116/0x280 security/security.c:1895
vfs_getattr fs/stat.c:259 [inline]
vfs_statx_path fs/stat.c:299 [inline]
vfs_statx+0x11f/0x3f0 fs/stat.c:356
vfs_fstatat+0x77/0xe0 fs/stat.c:373
__do_sys_newfstatat+0x9d/0x120 fs/stat.c:538
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff88803cb81900: 00 00 00 00 00 00 00 00 00 00 00 00 02 fc fc fc
ffff88803cb81980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803cb81a00: 00 00 00 00 00 00 00 00 00 00 00 00 02 fc fc fc
^
ffff88803cb81a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88803cb81b00: 00 00 00 00 00 00 00 00 00 00 00 00 02 fc fc fc
==================================================================
----------------
Code disassembly (best guess):
0: 68 46 ae ff 4c push $0x4cffae46
5: 89 f0 mov %esi,%eax
7: 48 85 c0 test %rax,%rax
a: 0f 85 bf 00 00 00 jne 0xcf
10: e8 77 4c ae ff call 0xffae4c8c
15: 0f 01 cb stac
18: 0f ae e8 lfence
1b: 4c 89 fb mov %r15,%rbx
1e: 4d 85 ff test %r15,%r15
21: 75 31 jne 0x54
23: eb 48 jmp 0x6d
25: e8 62 4c ae ff call 0xffae4c8c
* 2a: 44 8a 33 mov (%rbx),%r14b <-- trapping instruction
2d: e8 5a 4c ae ff call 0xffae4c8c
32: 48 81 c3 00 10 00 00 add $0x1000,%rbx
39: 31 ff xor %edi,%edi
3b: 48 rex.W
3c: 81 .byte 0x81
3d: e3 00 jrcxz 0x3f
3f: f0 lock
Tested on:
commit: 3eb40771 Merge tag 'soc-fixes-7.2-3' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1265e949580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=b72767277f29b6407083
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch: https://syzkaller.appspot.com/x/patch.diff?x=1197b279580000
^ permalink raw reply [flat|nested] 5+ messages in thread
* Forwarded: Re: [syzbot] [bridge?] KASAN: use-after-free Read in filemap_map_pages
2026-06-01 11:47 [syzbot] [net?] KASAN: use-after-free Read in filemap_map_pages syzbot
2026-08-15 12:51 ` [syzbot] [bridge?] " syzbot
@ 2026-08-16 6:43 ` syzbot
1 sibling, 0 replies; 5+ messages in thread
From: syzbot @ 2026-08-16 6:43 UTC (permalink / raw)
To: linux-kernel, syzkaller-bugs
For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.
***
Subject: Re: [syzbot] [bridge?] KASAN: use-after-free Read in filemap_map_pages
Author: idosch@nvidia.com
#syz unset subsystems
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2026-08-16 6:43 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-06-01 11:47 [syzbot] [net?] KASAN: use-after-free Read in filemap_map_pages syzbot
2026-08-15 12:51 ` [syzbot] [bridge?] " syzbot
2026-08-16 2:17 ` Hillf Danton
2026-08-16 2:34 ` syzbot
2026-08-16 6:43 ` Forwarded: " syzbot
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