[syzbot] KASAN: use-after-free Read in bdev_free_inode

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b7213ffa0e58 qnx4: avoid stringop-overread errors
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=107afc79300000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d93fe4341f98704
dashboard link: https://syzkaller.appspot.com/bug?extid=8281086e8a6fbfbd952a
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+828108...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in bdev_free_inode+0x202/0x220 block/bdev.c:407
Read of size 8 at addr ffff88807b26d948 by task ksoftirqd/0/13

CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
bdev_free_inode+0x202/0x220 block/bdev.c:407
i_callback+0x3f/0x70 fs/inode.c:224
rcu_do_batch kernel/rcu/tree.c:2508 [inline]
rcu_core+0x7ab/0x1470 kernel/rcu/tree.c:2743
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
run_ksoftirqd kernel/softirq.c:920 [inline]
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Allocated by task 9035:
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+0xa4/0xd0 mm/kasan/common.c:522
kmalloc_node include/linux/slab.h:609 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
__alloc_disk_node+0x77/0x580 block/genhd.c:1238
__blk_mq_alloc_disk+0xed/0x160 block/blk-mq.c:3140
loop_add+0x340/0x960 drivers/block/loop.c:2344
loop_control_ioctl+0x130/0x4a0 drivers/block/loop.c:2512
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
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 9035:
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+0xff/0x130 mm/kasan/common.c:374
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1700 [inline]
slab_free_freelist_hook+0x81/0x190 mm/slub.c:1725
slab_free mm/slub.c:3483 [inline]
kfree+0xe4/0x530 mm/slub.c:4543
__alloc_disk_node+0x474/0x580 block/genhd.c:1275
__blk_mq_alloc_disk+0xed/0x160 block/blk-mq.c:3140
loop_add+0x340/0x960 drivers/block/loop.c:2344
loop_control_ioctl+0x130/0x4a0 drivers/block/loop.c:2512
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
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 ffff88807b26d800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 328 bytes inside of
1024-byte region [ffff88807b26d800, ffff88807b26dc00)
The buggy address belongs to the page:
page:ffffea0001ec9a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7b268
head:ffffea0001ec9a00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c41dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6541, ts 204759478755, free_ts 204758542274
prep_new_page mm/page_alloc.c:2424 [inline]
get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4153
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5375
alloc_pages+0x1a7/0x300 mm/mempolicy.c:2197
alloc_slab_page mm/slub.c:1763 [inline]
allocate_slab mm/slub.c:1900 [inline]
new_slab+0x319/0x490 mm/slub.c:1963
___slab_alloc+0x921/0xfe0 mm/slub.c:2994
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3081
slab_alloc_node mm/slub.c:3172 [inline]
__kmalloc_node_track_caller+0x2d2/0x340 mm/slub.c:4936
kmalloc_reserve net/core/skbuff.c:355 [inline]
__alloc_skb+0xde/0x340 net/core/skbuff.c:426
alloc_skb include/linux/skbuff.h:1116 [inline]
__tcp_send_ack.part.0+0x67/0x7a0 net/ipv4/tcp_output.c:3946
__tcp_send_ack net/ipv4/tcp_output.c:3978 [inline]
tcp_send_ack+0x7d/0xa0 net/ipv4/tcp_output.c:3978
tcp_cleanup_rbuf+0x464/0x5a0 net/ipv4/tcp.c:1601
tcp_recvmsg_locked+0x7a2/0x2320 net/ipv4/tcp.c:2522
tcp_recvmsg+0x134/0x550 net/ipv4/tcp.c:2552
inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:852
sock_recvmsg_nosec net/socket.c:944 [inline]
sock_recvmsg net/socket.c:962 [inline]
sock_recvmsg net/socket.c:958 [inline]
sock_read_iter+0x353/0x490 net/socket.c:1035
call_read_iter include/linux/fs.h:2157 [inline]
new_sync_read+0x590/0x6b0 fs/read_write.c:404
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1338 [inline]
free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1389
free_unref_page_prepare mm/page_alloc.c:3315 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3394
__put_page+0x105/0x400 mm/swap.c:127
put_page include/linux/mm.h:1247 [inline]
__skb_frag_unref include/linux/skbuff.h:3107 [inline]
skb_release_data+0x49d/0x790 net/core/skbuff.c:671
skb_release_all net/core/skbuff.c:741 [inline]
__kfree_skb+0x46/0x60 net/core/skbuff.c:755
sk_eat_skb include/net/sock.h:2596 [inline]
tcp_recvmsg_locked+0x12f7/0x2320 net/ipv4/tcp.c:2506
tcp_recvmsg+0x134/0x550 net/ipv4/tcp.c:2552
inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:852
sock_recvmsg_nosec net/socket.c:944 [inline]
sock_recvmsg net/socket.c:962 [inline]
sock_recvmsg net/socket.c:958 [inline]
sock_read_iter+0x353/0x490 net/socket.c:1035
call_read_iter include/linux/fs.h:2157 [inline]
new_sync_read+0x590/0x6b0 fs/read_write.c:404
vfs_read+0x35c/0x600 fs/read_write.c:485
ksys_read+0x1ee/0x250 fs/read_write.c:623
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

Memory state around the buggy address:
ffff88807b26d800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b26d880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807b26d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807b26d980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b26da00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[Tetsuo Handa]

This seems to be kfree() before RCU grace period.

struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
{
struct block_device *bdev;
struct inode *inode;

inode = new_inode(blockdev_superblock);
if (!inode)
return NULL;
inode->i_mode = S_IFBLK;
inode->i_rdev = 0;
inode->i_data.a_ops = &def_blk_aops;
mapping_set_gfp_mask(&inode->i_data, GFP_USER);

bdev = I_BDEV(inode);
mutex_init(&bdev->bd_fsfreeze_mutex);
spin_lock_init(&bdev->bd_size_lock);
bdev->bd_disk = disk; // <= Assigns pointer to "disk".
bdev->bd_partno = partno;
bdev->bd_inode = inode;
bdev->bd_stats = alloc_percpu(struct disk_stats);
if (!bdev->bd_stats) {
iput(inode); // <= Will call bdev_free_inode() via i_callback() after RCU from destroy_inode() from evict() from iput_final() from iput().
return NULL;
}
return bdev;
}

struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
struct lock_class_key *lkclass)
{
struct gendisk *disk;

if (!blk_get_queue(q))
return NULL;

disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
if (!disk)
goto out_put_queue;

disk->bdi = bdi_alloc(node_id);
if (!disk->bdi)
goto out_free_disk;

disk->part0 = bdev_alloc(disk, 0);
if (!disk->part0)
goto out_free_bdi;

disk->node_id = node_id;
mutex_init(&disk->open_mutex);
xa_init(&disk->part_tbl);
if (xa_insert(&disk->part_tbl, 0, disk->part0, GFP_KERNEL))
goto out_destroy_part_tbl;

rand_initialize_disk(disk);
disk_to_dev(disk)->class = &block_class;
disk_to_dev(disk)->type = &disk_type;
device_initialize(disk_to_dev(disk));
inc_diskseq(disk);
disk->queue = q;
q->disk = disk;
lockdep_init_map(&disk->lockdep_map, "(bio completion)", lkclass, 0);
#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
INIT_LIST_HEAD(&disk->slave_bdevs);
#endif
return disk;

out_destroy_part_tbl:
xa_destroy(&disk->part_tbl);
iput(disk->part0->bd_inode); // <= The same race problem exists?
out_free_bdi:
bdi_put(disk->bdi);
out_free_disk:
kfree(disk); // <= Releasing "disk" despite "disk->part0->bd_disk == disk" when bdev_free_inode() will dereference ->bd_disk after RCU.
out_put_queue:
blk_put_queue(q);
return NULL;
}

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 741668ef7832 Merge tag 'usb-5.15-rc5' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=101a9d00b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=76f7496a8217e5ec

dashboard link: https://syzkaller.appspot.com/bug?extid=8281086e8a6fbfbd952a
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=170487b7300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+828108...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in bdev_free_inode+0x202/0x220 block/bdev.c:407

Read of size 8 at addr ffff88806e022148 by task systemd-udevd/8843

CPU: 1 PID: 8843 Comm: systemd-udevd Not tainted 5.15.0-rc4-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:106

print_address_description.constprop.0.cold+0x6c/0x2d6 mm/kasan/report.c:256

__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
bdev_free_inode+0x202/0x220 block/bdev.c:407

i_callback+0x3f/0x70 fs/inode.c:226

rcu_do_batch kernel/rcu/tree.c:2508 [inline]
rcu_core+0x7ab/0x1470 kernel/rcu/tree.c:2743
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558

invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x123/0x180 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:1097
</IRQ>
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x77/0x80 kernel/kcov.c:272
Code: f0 72 27 41 0f b6 fb 41 0f b6 c9 48 83 c2 01 48 c7 44 30 e0 01 00 00 00 48 89 7c 30 e8 48 89 4c 30 f0 4c 89 54 d8 20 48 89 10 <5b> c3 0f 1f 80 00 00 00 00 53 41 89 fb 41 89 f1 bf 03 00 00 00 65
RSP: 0018:ffffc9000ddef8f8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff888075942040
RDX: 0000000000000000 RSI: ffff888075942040 RDI: 0000000000000003
RBP: ffff88801e525f00 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff83a9492a R11: 0000000000000010 R12: 0000000000000002
R13: 000000000000010d R14: dffffc0000000000 R15: 0000000000000000
tomoyo_domain_quota_is_ok+0x32a/0x550 security/tomoyo/util.c:1092
tomoyo_supervisor+0x2f2/0xf00 security/tomoyo/common.c:2089
tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
tomoyo_path_permission security/tomoyo/file.c:587 [inline]
tomoyo_path_permission+0x270/0x3a0 security/tomoyo/file.c:573
tomoyo_path_perm+0x2f0/0x400 security/tomoyo/file.c:838
security_inode_getattr+0xcf/0x140 security/security.c:1333
vfs_getattr fs/stat.c:157 [inline]
vfs_fstat+0x43/0xb0 fs/stat.c:182
__do_sys_newfstat+0x81/0x100 fs/stat.c:422

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: 0033:0x7fc02b7062e2
Code: 48 8b 05 b9 db 2b 00 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 83 ff 01 77 33 48 63 fe b8 05 00 00 00 48 89 d6 0f 05 <48> 3d 00 f0 ff ff 77 06 f3 c3 0f 1f 40 00 48 8b 15 81 db 2b 00 f7
RSP: 002b:00007fffd25fb168 EFLAGS: 00000246 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 00007fc02b9c1440 RCX: 00007fc02b7062e2
RDX: 00007fffd25fb170 RSI: 00007fffd25fb170 RDI: 0000000000000007
RBP: 000055a86b68e0d0 R08: 00007fc02c8948c0 R09: 0000000000000230
R10: 000055a869f246bb R11: 0000000000000246 R12: 000055a869f246bb
R13: 0000000000000002 R14: 00007fc02b9c1440 R15: 0000000000000002

Allocated by task 15227:

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+0xa1/0xd0 mm/kasan/common.c:522
kasan_kmalloc include/linux/kasan.h:264 [inline]
kmem_cache_alloc_node_trace+0x20b/0x5d0 mm/slab.c:3619

kmalloc_node include/linux/slab.h:609 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
__alloc_disk_node+0x77/0x580 block/genhd.c:1238
__blk_mq_alloc_disk+0xed/0x160 block/blk-mq.c:3140
loop_add+0x340/0x960 drivers/block/loop.c:2344

loop_control_get_free drivers/block/loop.c:2501 [inline]
loop_control_ioctl+0x227/0x4a0 drivers/block/loop.c:2516

vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
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 15227:

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+0xd1/0x110 mm/kasan/common.c:374
kasan_slab_free include/linux/kasan.h:230 [inline]
__cache_free mm/slab.c:3445 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3803

__alloc_disk_node+0x474/0x580 block/genhd.c:1275
__blk_mq_alloc_disk+0xed/0x160 block/blk-mq.c:3140
loop_add+0x340/0x960 drivers/block/loop.c:2344

loop_control_get_free drivers/block/loop.c:2501 [inline]
loop_control_ioctl+0x227/0x4a0 drivers/block/loop.c:2516

vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
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

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xa7/0xd0 mm/kasan/generic.c:348
kvfree_call_rcu+0x74/0x990 kernel/rcu/tree.c:3552
neigh_destroy+0x419/0x620 net/core/neighbour.c:859
neigh_release include/net/neighbour.h:425 [inline]
neigh_cleanup_and_release+0x1fd/0x340 net/core/neighbour.c:103
neigh_del net/core/neighbour.c:197 [inline]
neigh_remove_one+0x37d/0x460 net/core/neighbour.c:218
neigh_forced_gc net/core/neighbour.c:248 [inline]
neigh_alloc net/core/neighbour.c:395 [inline]
___neigh_create+0x1799/0x26b0 net/core/neighbour.c:583
ip6_finish_output2+0x1089/0x1500 net/ipv6/ip6_output.c:123
__ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
__ip6_finish_output+0x4c1/0x1050 net/ipv6/ip6_output.c:170
ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224
dst_output include/net/dst.h:450 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508
ndisc_send_rs+0x12e/0x6f0 net/ipv6/ndisc.c:702
addrconf_rs_timer+0x3f2/0x820 net/ipv6/addrconf.c:3893
call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421
expire_timers kernel/time/timer.c:1466 [inline]
__run_timers.part.0+0x675/0xa20 kernel/time/timer.c:1734
__run_timers kernel/time/timer.c:1715 [inline]
run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558

The buggy address belongs to the object at ffff88806e022000

which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 328 bytes inside of

1024-byte region [ffff88806e022000, ffff88806e022400)

The buggy address belongs to the page:

page:ffffea0001b80880 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88806e022800 pfn:0x6e022
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00006c07c8 ffffea0000846d88 ffff888010c40700
raw: ffff88806e022800 ffff88806e022000 0000000100000001 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 0x2c2220(__GFP_HIGH|__GFP_ATOMIC|__GFP_NOWARN|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_THISNODE), pid 158, ts 99636399470, free_ts 99492418189

prep_new_page mm/page_alloc.c:2424 [inline]
get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4153
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5375

__alloc_pages_node include/linux/gfp.h:570 [inline]
kmem_getpages mm/slab.c:1377 [inline]
cache_grow_begin+0x75/0x460 mm/slab.c:2593
cache_alloc_refill+0x27f/0x380 mm/slab.c:2965
____cache_alloc mm/slab.c:3048 [inline]
____cache_alloc mm/slab.c:3031 [inline]
slab_alloc_node mm/slab.c:3249 [inline]
kmem_cache_alloc_node_trace+0x4ca/0x5d0 mm/slab.c:3617
__do_kmalloc_node mm/slab.c:3639 [inline]
__kmalloc_node_track_caller+0x38/0x60 mm/slab.c:3654

kmalloc_reserve net/core/skbuff.c:355 [inline]
__alloc_skb+0xde/0x340 net/core/skbuff.c:426
alloc_skb include/linux/skbuff.h:1116 [inline]

wg_socket_send_buffer_to_peer+0x2f/0x170 drivers/net/wireguard/socket.c:191
wg_packet_send_handshake_initiation+0x212/0x340 drivers/net/wireguard/send.c:40
wg_packet_handshake_send_worker+0x18/0x30 drivers/net/wireguard/send.c:51
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
worker_thread+0x658/0x11f0 kernel/workqueue.c:2444

kthread+0x3e5/0x4d0 kernel/kthread.c:319
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:1338 [inline]
free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1389
free_unref_page_prepare mm/page_alloc.c:3315 [inline]

free_unref_page_list+0x1a9/0xfa0 mm/page_alloc.c:3431
release_pages+0x830/0x20b0 mm/swap.c:963
tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
tlb_flush_mmu mm/mmu_gather.c:249 [inline]
tlb_finish_mmu+0x165/0x8c0 mm/mmu_gather.c:340
exit_mmap+0x1ea/0x630 mm/mmap.c:3173
__mmput+0x122/0x4b0 kernel/fork.c:1115
mmput+0x58/0x60 kernel/fork.c:1136
free_bprm+0x65/0x2e0 fs/exec.c:1483
kernel_execve+0x380/0x460 fs/exec.c:1980
call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:

ffff88806e022000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88806e022080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88806e022100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88806e022180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88806e022200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: f0 72 27 lock jb 0x2a
3: 41 0f b6 fb movzbl %r11b,%edi
7: 41 0f b6 c9 movzbl %r9b,%ecx
b: 48 83 c2 01 add $0x1,%rdx
f: 48 c7 44 30 e0 01 00 movq $0x1,-0x20(%rax,%rsi,1)
16: 00 00
18: 48 89 7c 30 e8 mov %rdi,-0x18(%rax,%rsi,1)
1d: 48 89 4c 30 f0 mov %rcx,-0x10(%rax,%rsi,1)
22: 4c 89 54 d8 20 mov %r10,0x20(%rax,%rbx,8)
27: 48 89 10 mov %rdx,(%rax)
* 2a: 5b pop %rbx <-- trapping instruction
2b: c3 retq
2c: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
33: 53 push %rbx
34: 41 89 fb mov %edi,%r11d
37: 41 89 f1 mov %esi,%r9d
3a: bf 03 00 00 00 mov $0x3,%edi
3f: 65 gs

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+828108...@syzkaller.appspotmail.com

Tested on:

commit: 5d6ab0bb Merge tag 'xtensa-20211008' of git://github.c..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=f2f08ce63e886513

dashboard link: https://syzkaller.appspot.com/bug?extid=8281086e8a6fbfbd952a
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=14012de0b00000

Note: testing is done by a robot and is best-effort only.

[syzbot]

> Commit 06cc978d3ff22607 in axboe/linux-block.git#block-5.15
>
> #syz fix: block: genhd: fix double kfree() in __alloc_disk_node()

Your 'fix:' command is accepted, but please keep syzkall...@googlegroups.com mailing list in CC next time. It serves as a history of what happened with each bug report. Thank you.

>