Re: [syzbot] [mm?] WARNING in __folio_rmap_sanity_checks (2)

syzbot
2024-12-30T11:49:04Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in filemap_map_pages

==================================================================
BUG: KASAN: slab-use-after-free in ptep_get include/linux/pgtable.h:338 [inline]
BUG: KASAN: slab-use-after-free in filemap_map_folio_range mm/filemap.c:3632 [inline]
BUG: KASAN: slab-use-after-free in filemap_map_pages+0xdba/0x1ab0 mm/filemap.c:3753
Read of size 8 at addr ffff888063e5c000 by task syz.0.22/6900

CPU: 0 UID: 0 PID: 6900 Comm: syz.0.22 Not tainted 6.13.0-rc3-next-20241220-syzkaller-05236-g8155b4ef3466-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x169/0x550 mm/kasan/report.c:489
kasan_report+0x143/0x180 mm/kasan/report.c:602
ptep_get include/linux/pgtable.h:338 [inline]
filemap_map_folio_range mm/filemap.c:3632 [inline]
filemap_map_pages+0xdba/0x1ab0 mm/filemap.c:3753
do_fault_around mm/memory.c:5351 [inline]
do_read_fault mm/memory.c:5384 [inline]
do_fault mm/memory.c:5527 [inline]
do_pte_missing mm/memory.c:4048 [inline]
handle_pte_fault+0x3888/0x5ee0 mm/memory.c:5890
__handle_mm_fault mm/memory.c:6033 [inline]
handle_mm_fault+0x11f5/0x1d50 mm/memory.c:6202
faultin_page mm/gup.c:1196 [inline]
__get_user_pages+0x1a92/0x4140 mm/gup.c:1491
populate_vma_page_range+0x264/0x330 mm/gup.c:1929
__mm_populate+0x27a/0x460 mm/gup.c:2032
mm_populate include/linux/mm.h:3400 [inline]
vm_mmap_pgoff+0x303/0x430 mm/util.c:585
ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:607
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe194b85d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe195969038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fe194d76080 RCX: 00007fe194b85d29
RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000000020000000
RBP: 00007fe194c01b08 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe194d76080 R15: 00007ffe2c0aa718
</TASK>

Allocated by task 25:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:319 [inline]
__kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4115 [inline]
slab_alloc_node mm/slub.c:4164 [inline]
kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4171
dst_alloc+0x12b/0x190 net/core/dst.c:89
ip6_dst_alloc net/ipv6/route.c:342 [inline]
icmp6_dst_alloc+0x77/0x420 net/ipv6/route.c:3275
mld_sendpack+0x6a3/0xdb0 net/ipv6/mcast.c:1849
mld_send_cr net/ipv6/mcast.c:2161 [inline]
mld_ifc_work+0x7d9/0xd90 net/ipv6/mcast.c:2695
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
worker_thread+0x870/0xd30 kernel/workqueue.c:3391
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Freed by task 35:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2353 [inline]
slab_free mm/slub.c:4609 [inline]
kmem_cache_free+0x195/0x410 mm/slub.c:4711
dst_destroy+0x249/0x360 net/core/dst.c:121
rcu_do_batch kernel/rcu/tree.c:2546 [inline]
rcu_core+0xaaa/0x17a0 kernel/rcu/tree.c:2802
handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561
__do_softirq kernel/softirq.c:595 [inline]
invoke_softirq kernel/softirq.c:435 [inline]
__irq_exit_rcu+0xf7/0x220 kernel/softirq.c:662
irq_exit_rcu+0x9/0x30 kernel/softirq.c:678
instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
sysvec_irq_work+0xa3/0xc0 arch/x86/kernel/irq_work.c:17
asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:738

Last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
kasan_record_aux_stack+0xaa/0xc0 mm/kasan/generic.c:548
__call_rcu_common kernel/rcu/tree.c:3065 [inline]
call_rcu+0x168/0xac0 kernel/rcu/tree.c:3172
refdst_drop include/net/dst.h:263 [inline]
skb_dst_drop include/net/dst.h:275 [inline]
__dev_queue_xmit+0x87b/0x3f50 net/core/dev.c:4389
neigh_output include/net/neighbour.h:539 [inline]
ip6_finish_output2+0x12ad/0x1780 net/ipv6/ip6_output.c:141
ip6_finish_output+0x41e/0x840 net/ipv6/ip6_output.c:226
NF_HOOK+0x9e/0x430 include/linux/netfilter.h:314
mld_sendpack+0x843/0xdb0 net/ipv6/mcast.c:1860
mld_send_cr net/ipv6/mcast.c:2161 [inline]
mld_ifc_work+0x7d9/0xd90 net/ipv6/mcast.c:2695
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
worker_thread+0x870/0xd30 kernel/workqueue.c:3391
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff888063e5c000
which belongs to the cache ip6_dst_cache of size 232
The buggy address is located 0 bytes inside of
freed 232-byte region [ffff888063e5c000, ffff888063e5c0e8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x63e5c
memcg:ffff888063f79c01
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88814ca24500 dead000000000122 0000000000000000
raw: 0000000000000000 00000000000c000c 00000000f5000000 ffff888063f79c01
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 25, tgid 25 (kworker/1:0), ts 121780402212, free_ts 107625052788
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551
prep_new_page mm/page_alloc.c:1559 [inline]
get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3477
__alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4754
alloc_pages_mpol+0x30e/0x550 mm/mempolicy.c:2270
alloc_slab_page mm/slub.c:2423 [inline]
allocate_slab+0x8f/0x3a0 mm/slub.c:2587
new_slab mm/slub.c:2640 [inline]
___slab_alloc+0xc27/0x14a0 mm/slub.c:3826
__slab_alloc+0x58/0xa0 mm/slub.c:3916
__slab_alloc_node mm/slub.c:3991 [inline]
slab_alloc_node mm/slub.c:4152 [inline]
kmem_cache_alloc_noprof+0x268/0x380 mm/slub.c:4171
dst_alloc+0x12b/0x190 net/core/dst.c:89
ip6_dst_alloc net/ipv6/route.c:342 [inline]
icmp6_dst_alloc+0x77/0x420 net/ipv6/route.c:3275
mld_sendpack+0x6a3/0xdb0 net/ipv6/mcast.c:1849
mld_send_cr net/ipv6/mcast.c:2161 [inline]
mld_ifc_work+0x7d9/0xd90 net/ipv6/mcast.c:2695
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
worker_thread+0x870/0xd30 kernel/workqueue.c:3391
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
page last free pid 6533 tgid 6533 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1127 [inline]
free_frozen_pages+0xe0d/0x10e0 mm/page_alloc.c:2660
vfree+0x1c3/0x360 mm/vmalloc.c:3383
kcov_put kernel/kcov.c:439 [inline]
kcov_close+0x28/0x50 kernel/kcov.c:535
__fput+0x3e9/0x9f0 fs/file_table.c:450
task_work_run+0x24f/0x310 kernel/task_work.c:227
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0xa2f/0x28e0 kernel/exit.c:938
do_group_exit+0x207/0x2c0 kernel/exit.c:1087
get_signal+0x16b2/0x1750 kernel/signal.c:3017
arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff888063e5bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888063e5bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888063e5c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888063e5c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff888063e5c100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: 8155b4ef Add linux-next specific files for 20241220
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1454550f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=9c90bb7161a56c88
dashboard link: https://syzkaller.appspot.com/bug?extid=c0673e1f1f054fac28c2
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=142ef0b0580000