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

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May 12, 2021, 5:40:22 AMMay 12
to da...@davemloft.net, ku...@kernel.org, linu...@vger.kernel.org, linux-...@vger.kernel.org, m...@pengutronix.de, net...@vger.kernel.org, sock...@hartkopp.net, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 009fc857 mISDN: fix possible use-after-free in HFC_cleanup()
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11ce90add00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b072be26137971e1
dashboard link: https://syzkaller.appspot.com/bug?extid=0f7e7e5e2f4f40fa89c0
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17c9f9b3d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0f7e7e...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in bcm_rx_starttimer net/can/bcm.c:543 [inline]
BUG: KASAN: use-after-free in bcm_rx_handler+0x5ff/0x6d0 net/can/bcm.c:694
Read of size 4 at addr ffff88802af28418 by task syz-executor.1/10095

CPU: 1 PID: 10095 Comm: syz-executor.1 Not tainted 5.12.0-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:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:233
__kasan_report mm/kasan/report.c:419 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:436
bcm_rx_starttimer net/can/bcm.c:543 [inline]
bcm_rx_handler+0x5ff/0x6d0 net/can/bcm.c:694
deliver net/can/af_can.c:574 [inline]
can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635
can_receive+0x290/0x580 net/can/af_can.c:661
can_rcv+0x120/0x1c0 net/can/af_can.c:696
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5440
__netif_receive_skb+0x27/0x1c0 net/core/dev.c:5554
process_backlog+0x232/0x6c0 net/core/dev.c:6418
__napi_poll+0xaf/0x440 net/core/dev.c:6966
napi_poll net/core/dev.c:7033 [inline]
net_rx_action+0x801/0xb40 net/core/dev.c:7120
__do_softirq+0x29b/0x9f6 kernel/softirq.c:559
do_softirq.part.0+0xd9/0x130 kernel/softirq.c:460
</IRQ>
netif_rx_ni+0x33d/0x590 net/core/dev.c:4966
can_send+0x4ec/0x9a0 net/can/af_can.c:287
isotp_sendmsg+0x8c2/0x13d0 net/can/isotp.c:946
sock_sendmsg_nosec net/socket.c:654 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:674
____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
___sys_sendmsg+0xf3/0x170 net/socket.c:2404
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665f9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff4a7a7d188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9
RDX: 0000000000000004 RSI: 00000000200003c0 RDI: 0000000000000004
RBP: 00000000004bfce1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe23e0924f R14: 00007ff4a7a7d300 R15: 0000000000022000

Allocated by task 10111:
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:428 [inline]
____kasan_kmalloc mm/kasan/common.c:507 [inline]
____kasan_kmalloc mm/kasan/common.c:466 [inline]
__kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:516
kmalloc include/linux/slab.h:556 [inline]
kzalloc include/linux/slab.h:686 [inline]
bcm_rx_setup net/can/bcm.c:1070 [inline]
bcm_sendmsg+0x2a81/0x4420 net/can/bcm.c:1331
sock_sendmsg_nosec net/socket.c:654 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:674
____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
___sys_sendmsg+0xf3/0x170 net/socket.c:2404
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 10093:
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:357
____kasan_slab_free mm/kasan/common.c:360 [inline]
____kasan_slab_free mm/kasan/common.c:325 [inline]
__kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368
kasan_slab_free include/linux/kasan.h:212 [inline]
slab_free_hook mm/slub.c:1581 [inline]
slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1606
slab_free mm/slub.c:3166 [inline]
kfree+0xe5/0x7f0 mm/slub.c:4225
bcm_release+0x34a/0x780 net/can/bcm.c:1506
__sock_release+0xcd/0x280 net/socket.c:599
sock_close+0x18/0x20 net/socket.c:1258
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x272/0x280 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:57
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88802af28400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
512-byte region [ffff88802af28400, ffff88802af28600)
The buggy address belongs to the page:
page:ffffea0000abca00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2af28
head:ffffea0000abca00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888011041c80
raw: 0000000000000000 0000000000100010 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 8455, ts 309324953429, free_ts 309319650475
prep_new_page mm/page_alloc.c:2358 [inline]
get_page_from_freelist+0x1033/0x2b60 mm/page_alloc.c:3994
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5200
alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272
alloc_slab_page mm/slub.c:1644 [inline]
allocate_slab+0x2c5/0x4c0 mm/slub.c:1784
new_slab mm/slub.c:1847 [inline]
new_slab_objects mm/slub.c:2593 [inline]
___slab_alloc+0x44c/0x7a0 mm/slub.c:2756
__slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2796
slab_alloc_node mm/slub.c:2878 [inline]
__kmalloc_node_track_caller+0x2e6/0x350 mm/slub.c:4604
kmalloc_reserve net/core/skbuff.c:354 [inline]
__alloc_skb+0xde/0x340 net/core/skbuff.c:425
alloc_skb include/linux/skbuff.h:1107 [inline]
nlmsg_new include/net/netlink.h:953 [inline]
netlink_ack+0x1ed/0xaa0 net/netlink/af_netlink.c:2437
netlink_rcv_skb+0x33d/0x420 net/netlink/af_netlink.c:2508
netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
sock_sendmsg_nosec net/socket.c:654 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:674
__sys_sendto+0x21c/0x320 net/socket.c:1977
__do_sys_sendto net/socket.c:1989 [inline]
__se_sys_sendto net/socket.c:1985 [inline]
__x64_sys_sendto+0xdd/0x1b0 net/socket.c:1985
do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1298 [inline]
__free_pages_ok+0x476/0xce0 mm/page_alloc.c:1572
stack_depot_save+0x162/0x4e0 lib/stackdepot.c:336
kasan_save_stack+0x32/0x40 mm/kasan/common.c:40
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:428 [inline]
__kasan_slab_alloc+0x84/0xa0 mm/kasan/common.c:461
kasan_slab_alloc include/linux/kasan.h:236 [inline]
slab_post_alloc_hook mm/slab.h:524 [inline]
slab_alloc_node mm/slub.c:2912 [inline]
slab_alloc mm/slub.c:2920 [inline]
kmem_cache_alloc+0x152/0x3a0 mm/slub.c:2925
alloc_inode+0x161/0x230 fs/inode.c:235
new_inode_pseudo fs/inode.c:934 [inline]
new_inode+0x27/0x2f0 fs/inode.c:963
debugfs_get_inode+0x1a/0x130 fs/debugfs/inode.c:69
__debugfs_create_file+0x11a/0x4e0 fs/debugfs/inode.c:404
debugfs_create_mode_unsafe fs/debugfs/file.c:407 [inline]
debugfs_create_bool+0x6c/0xa0 fs/debugfs/file.c:862
nsim_dev_debugfs_init drivers/net/netdevsim/dev.c:231 [inline]
nsim_dev_probe+0xa9d/0x1080 drivers/net/netdevsim/dev.c:1109
really_probe+0x291/0xf60 drivers/base/dd.c:576
driver_probe_device+0x298/0x410 drivers/base/dd.c:763
__device_attach_driver+0x203/0x2c0 drivers/base/dd.c:870
bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:431
__device_attach+0x228/0x4b0 drivers/base/dd.c:938

Memory state around the buggy address:
ffff88802af28300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802af28380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802af28400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802af28480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802af28500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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unread,
May 12, 2021, 6:13:06 AMMay 12
to da...@davemloft.net, ku...@kernel.org, linu...@vger.kernel.org, linux-...@vger.kernel.org, m...@pengutronix.de, net...@vger.kernel.org, sock...@hartkopp.net, syzkall...@googlegroups.com
syzbot has bisected this issue to:

commit e057dd3fc20ffb3d7f150af46542a51b59b90127
Author: Oliver Hartkopp <sock...@hartkopp.net>
Date: Mon Sep 28 20:04:04 2020 +0000

can: add ISO 15765-2:2016 transport protocol

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16883835d00000
start commit: 009fc857 mISDN: fix possible use-after-free in HFC_cleanup()
git tree: net-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=15883835d00000
console output: https://syzkaller.appspot.com/x/log.txt?x=11883835d00000
Reported-by: syzbot+0f7e7e...@syzkaller.appspotmail.com
Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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