KASAN: use-after-free Read in sg_release

[Rondreis]

Hello,

When fuzzing the Linux kernel driver v6.0-rc6, the following crash was
triggered.

HEAD commit: 521a547ced6477c54b4b0cc206000406c221b4d6
git tree: upstream

kernel config: https://pastebin.com/raw/hekxU61F
console output: https://pastebin.com/raw/73a8RzBY

Sorry for failing to extract the reproducer. But on other versions of
Linux, I also triggered this crash.

I would appreciate it if you have any idea how to solve this bug.

The crash report is as follows:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read
include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_long_read
include/linux/atomic/atomic-instrumented.h:1265 [inline]
BUG: KASAN: use-after-free in __mutex_unlock_slowpath+0xac/0x610
kernel/locking/mutex.c:916
Read of size 8 at addr ffff888061b92c58 by task syz-executor.6/18641

CPU: 1 PID: 18641 Comm: syz-executor.6 Not tainted 6.0.0-rc4+ #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0xe5/0x66d mm/kasan/report.c:433
kasan_report+0x8a/0x1b0 mm/kasan/report.c:495
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13b/0x190 mm/kasan/generic.c:189
instrument_atomic_read include/linux/instrumented.h:71 [inline]
atomic_long_read include/linux/atomic/atomic-instrumented.h:1265 [inline]
__mutex_unlock_slowpath+0xac/0x610 kernel/locking/mutex.c:916
sg_release+0x204/0x320 drivers/scsi/sg.c:404
__fput+0x277/0x9d0 fs/file_table.c:320
task_work_run+0xe0/0x1a0 kernel/task_work.c:177
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop kernel/entry/common.c:169 [inline]
exit_to_user_mode_prepare+0x25d/0x270 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f492c03f60b
Code: 03 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c
24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d
00 f0 ff ff 77 2f 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007fffb71b9f80 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007f492c03f60b
RDX: ffffffffffffffb8 RSI: 0000001b2e8289d0 RDI: 0000000000000004
RBP: 00007f492c19dd4c R08: 0000000000000000 R09: 000000003acb2633
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000000b5109
R13: 00007fffb71ba0c0 R14: 00007f492c19c41c R15: 00000000000b4e47
</TASK>

Allocated by task 26:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:437 [inline]
____kasan_kmalloc mm/kasan/common.c:516 [inline]
____kasan_kmalloc mm/kasan/common.c:475 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525
kasan_kmalloc include/linux/kasan.h:234 [inline]
kmem_cache_alloc_trace+0x19b/0x380 mm/slub.c:3284
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
sg_alloc drivers/scsi/sg.c:1438 [inline]
sg_add_device+0x110/0xb10 drivers/scsi/sg.c:1507
device_add+0xf27/0x1da0 drivers/base/core.c:3541
scsi_sysfs_add_sdev+0x1ff/0x500 drivers/scsi/scsi_sysfs.c:1395
scsi_sysfs_add_devices drivers/scsi/scsi_scan.c:1812 [inline]
scsi_finish_async_scan drivers/scsi/scsi_scan.c:1897 [inline]
do_scan_async+0x20f/0x4f0 drivers/scsi/scsi_scan.c:1940
async_run_entry_fn+0x98/0x540 kernel/async.c:127
process_one_work+0x9c7/0x1650 kernel/workqueue.c:2289
worker_thread+0x623/0x1070 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Freed by task 2956:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:367 [inline]
____kasan_slab_free mm/kasan/common.c:329 [inline]
__kasan_slab_free+0x11d/0x1b0 mm/kasan/common.c:375
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1754 [inline]
slab_free_freelist_hook mm/slub.c:1780 [inline]
slab_free mm/slub.c:3534 [inline]
kfree+0xe9/0x650 mm/slub.c:4562
kref_put include/linux/kref.h:65 [inline]
sg_remove_sfp_usercontext+0x39f/0x5a0 drivers/scsi/sg.c:2243
process_one_work+0x9c7/0x1650 kernel/workqueue.c:2289
worker_thread+0x623/0x1070 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Last potentially related work creation:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
__kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
insert_work+0x4a/0x390 kernel/workqueue.c:1358
__queue_work+0x4d4/0x1200 kernel/workqueue.c:1517
call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
expire_timers kernel/time/timer.c:1514 [inline]
__run_timers.part.0+0x49e/0xad0 kernel/time/timer.c:1790
__run_timers kernel/time/timer.c:1768 [inline]
run_timer_softirq+0xb6/0x1d0 kernel/time/timer.c:1803
__do_softirq+0x1d0/0x908 kernel/softirq.c:571

Second to last potentially related work creation:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
__kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
call_rcu kernel/rcu/tree.c:2793 [inline]
call_rcu+0x99/0x740 kernel/rcu/tree.c:2768
fib6_info_release include/net/ip6_fib.h:340 [inline]
fib6_info_release include/net/ip6_fib.h:337 [inline]
fixup_permanent_addr net/ipv6/addrconf.c:3472 [inline]
addrconf_permanent_addr net/ipv6/addrconf.c:3500 [inline]
addrconf_notify+0x1661/0x1ba0 net/ipv6/addrconf.c:3568
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
call_netdevice_notifiers_info net/core/dev.c:1945 [inline]
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1930
call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
call_netdevice_notifiers net/core/dev.c:1997 [inline]
__dev_notify_flags+0x121/0x2c0 net/core/dev.c:8594
dev_change_flags+0x112/0x170 net/core/dev.c:8632
do_setlink+0xacc/0x3ca0 net/core/rtnetlink.c:2780
__rtnl_newlink+0xad1/0x16f0 net/core/rtnetlink.c:3546
rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3593
rtnetlink_rcv_msg+0x43a/0xca0 net/core/rtnetlink.c:6090
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x760 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg net/socket.c:734 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:729
__sys_sendto+0x236/0x340 net/socket.c:2117
__do_sys_sendto net/socket.c:2129 [inline]
__se_sys_sendto net/socket.c:2125 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:2125
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888061b92c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 88 bytes inside of
512-byte region [ffff888061b92c00, ffff888061b92e00)

The buggy address belongs to the physical page:
page:ffffea000186e400 refcount:1 mapcount:0 mapping:0000000000000000
index:0xffff888061b92400 pfn:0x61b90
head:ffffea000186e400 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4fff00000010200(slab|head|node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000010200 ffffea0001628408 ffffea00018a2708 ffff888011c41c80
raw: ffff888061b92400 000000000010000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask
0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL),
pid 2956, tgid 2956 (kworker/1:4), ts 243564663662, free_ts 0
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook mm/page_alloc.c:2525 [inline]
prep_new_page+0x2c6/0x350 mm/page_alloc.c:2532
get_page_from_freelist+0xae9/0x3a80 mm/page_alloc.c:4283
__alloc_pages+0x321/0x710 mm/page_alloc.c:5515
alloc_pages+0x117/0x2f0 mm/mempolicy.c:2270
alloc_slab_page mm/slub.c:1824 [inline]
allocate_slab mm/slub.c:1969 [inline]
new_slab+0x246/0x3a0 mm/slub.c:2029
___slab_alloc+0xa50/0x1060 mm/slub.c:3031
__slab_alloc.isra.0+0x4d/0xa0 mm/slub.c:3118
slab_alloc_node mm/slub.c:3209 [inline]
slab_alloc mm/slub.c:3251 [inline]
kmem_cache_alloc_trace+0x35b/0x380 mm/slub.c:3282
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
fib6_info_alloc+0xc3/0x210 net/ipv6/ip6_fib.c:156
ip6_route_info_create+0x33e/0x1ab0 net/ipv6/route.c:3749
addrconf_f6i_alloc+0x377/0x610 net/ipv6/route.c:4571
ipv6_add_addr+0x3a2/0x1e00 net/ipv6/addrconf.c:1105
addrconf_add_linklocal+0x1cf/0x3e0 net/ipv6/addrconf.c:3215
addrconf_addr_gen+0x396/0x3e0 net/ipv6/addrconf.c:3346
addrconf_dev_config+0x255/0x410 net/ipv6/addrconf.c:3391
addrconf_notify+0xddb/0x1ba0 net/ipv6/addrconf.c:3631
page_owner free stack trace missing

Memory state around the buggy address:
ffff888061b92b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888061b92b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888061b92c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888061b92c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061b92d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================