[syzbot] KASAN: use-after-free Read in em28xx_init_extension (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 52d543b5497c Merge tag 'for-linus-5.17-1' of https://githu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17b804fb700000
kernel config: https://syzkaller.appspot.com/x/.config?x=7094767cefc58fb9
dashboard link: https://syzkaller.appspot.com/bug?extid=99d6c66dbbc484f50e1c
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=161c4739700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16432d51700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+99d6c6...@syzkaller.appspotmail.com

em28xx 5-1:0.130: Config register raw data: 0xfffffffb
em28xx 5-1:0.130: AC97 chip type couldn't be determined
em28xx 5-1:0.130: No AC97 audio processor
==================================================================
BUG: KASAN: use-after-free in __list_add_valid+0x93/0xa0 lib/list_debug.c:26
Read of size 8 at addr ffff888027458250 by task kworker/1:1/40

CPU: 1 PID: 40 Comm: kworker/1:1 Not tainted 5.17.0-syzkaller-10752-g52d543b5497c #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313
print_report mm/kasan/report.c:429 [inline]
kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
__list_add_valid+0x93/0xa0 lib/list_debug.c:26
__list_add include/linux/list.h:69 [inline]
list_add_tail include/linux/list.h:102 [inline]
em28xx_init_extension+0x44/0x1f0 drivers/media/usb/em28xx/em28xx-core.c:1123
em28xx_init_dev.constprop.0+0xa8b/0x1746 drivers/media/usb/em28xx/em28xx-cards.c:3637
em28xx_usb_probe.cold+0xc29/0x258a drivers/media/usb/em28xx/em28xx-cards.c:3992
usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:517 [inline]
really_probe+0x245/0xcc0 drivers/base/dd.c:596
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:755
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:785
__device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:902
bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427
__device_attach+0x228/0x4a0 drivers/base/dd.c:973
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487
device_add+0xb83/0x1e20 drivers/base/core.c:3405
usb_set_configuration+0x101e/0x1900 drivers/usb/core/message.c:2170
usb_generic_driver_probe+0xba/0x100 drivers/usb/core/generic.c:238
usb_probe_device+0xd9/0x2c0 drivers/usb/core/driver.c:293
call_driver_probe drivers/base/dd.c:517 [inline]
really_probe+0x245/0xcc0 drivers/base/dd.c:596
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:755
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:785
__device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:902
bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427
__device_attach+0x228/0x4a0 drivers/base/dd.c:973
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487
device_add+0xb83/0x1e20 drivers/base/core.c:3405
usb_new_device.cold+0x641/0x1091 drivers/usb/core/hub.c:2566
hub_port_connect drivers/usb/core/hub.c:5358 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5502 [inline]
port_event drivers/usb/core/hub.c:5660 [inline]
hub_event+0x25c6/0x4680 drivers/usb/core/hub.c:5742
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
process_scheduled_works kernel/workqueue.c:2352 [inline]
worker_thread+0x854/0x1080 kernel/workqueue.c:2438
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

Allocated by task 40:
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:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:524
kasan_kmalloc include/linux/kasan.h:234 [inline]
__do_kmalloc mm/slab.c:3709 [inline]
__kmalloc_track_caller+0x206/0x4d0 mm/slab.c:3724
kmemdup+0x23/0x50 mm/util.c:128
kmemdup include/linux/fortify-string.h:304 [inline]
em28xx_duplicate_dev drivers/media/usb/em28xx/em28xx-cards.c:3690 [inline]
em28xx_usb_probe.cold+0x134a/0x258a drivers/media/usb/em28xx/em28xx-cards.c:4040
usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:517 [inline]
really_probe+0x245/0xcc0 drivers/base/dd.c:596
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:755
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:785
__device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:902
bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427
__device_attach+0x228/0x4a0 drivers/base/dd.c:973
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487
device_add+0xb83/0x1e20 drivers/base/core.c:3405
usb_set_configuration+0x101e/0x1900 drivers/usb/core/message.c:2170
usb_generic_driver_probe+0xba/0x100 drivers/usb/core/generic.c:238
usb_probe_device+0xd9/0x2c0 drivers/usb/core/driver.c:293
call_driver_probe drivers/base/dd.c:517 [inline]
really_probe+0x245/0xcc0 drivers/base/dd.c:596
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:755
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:785
__device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:902
bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427
__device_attach+0x228/0x4a0 drivers/base/dd.c:973
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487
device_add+0xb83/0x1e20 drivers/base/core.c:3405
usb_new_device.cold+0x641/0x1091 drivers/usb/core/hub.c:2566
hub_port_connect drivers/usb/core/hub.c:5358 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5502 [inline]
port_event drivers/usb/core/hub.c:5660 [inline]
hub_event+0x25c6/0x4680 drivers/usb/core/hub.c:5742
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 40:
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:366 [inline]
____kasan_slab_free+0x13d/0x180 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
__cache_free mm/slab.c:3438 [inline]
kfree+0xfb/0x2c0 mm/slab.c:3809
__refcount_sub_and_test include/linux/refcount.h:282 [inline]
__refcount_dec_and_test include/linux/refcount.h:315 [inline]
refcount_dec_and_test include/linux/refcount.h:333 [inline]
kref_put.constprop.0.isra.0+0x3d/0x7e include/linux/kref.h:64
em28xx_usb_disconnect.cold+0x1c2/0x237 drivers/media/usb/em28xx/em28xx-cards.c:4158
usb_unbind_interface+0x1d8/0x8e0 drivers/usb/core/driver.c:458
__device_release_driver+0x627/0x760 drivers/base/dd.c:1209
device_release_driver_internal drivers/base/dd.c:1242 [inline]
device_release_driver+0x26/0x40 drivers/base/dd.c:1265
bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:529
device_del+0x4f3/0xc80 drivers/base/core.c:3592
usb_disable_device+0x35b/0x7b0 drivers/usb/core/message.c:1419
usb_disconnect.cold+0x278/0x6ec drivers/usb/core/hub.c:2228
hub_port_connect drivers/usb/core/hub.c:5202 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5502 [inline]
port_event drivers/usb/core/hub.c:5660 [inline]
hub_event+0x1e74/0x4680 drivers/usb/core/hub.c:5742
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
process_scheduled_works kernel/workqueue.c:2352 [inline]
worker_thread+0x854/0x1080 kernel/workqueue.c:2438
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888027458000
which belongs to the cache kmalloc-16k of size 16384
The buggy address is located 592 bytes inside of
16384-byte region [ffff888027458000, ffff88802745c000)

The buggy address belongs to the physical page:
page:ffffea00009d1600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27458
head:ffffea00009d1600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea00008c5808 ffffea00009bf608 ffff888010c40b00
raw: 0000000000000000 ffff888027458000 0000000100000001 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 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 40, tgid 40 (kworker/1:1), ts 55959586532, free_ts 54110027164
prep_new_page mm/page_alloc.c:2438 [inline]
get_page_from_freelist+0xba2/0x3df0 mm/page_alloc.c:4179
__alloc_pages+0x1b2/0x500 mm/page_alloc.c:5405
__alloc_pages_node include/linux/gfp.h:589 [inline]
kmem_getpages mm/slab.c:1378 [inline]
cache_grow_begin+0x75/0x350 mm/slab.c:2584
cache_alloc_refill+0x27f/0x380 mm/slab.c:2957
____cache_alloc mm/slab.c:3040 [inline]
____cache_alloc mm/slab.c:3023 [inline]
__do_cache_alloc mm/slab.c:3267 [inline]
slab_alloc mm/slab.c:3309 [inline]
__do_kmalloc mm/slab.c:3707 [inline]
__kmalloc_track_caller+0x3b0/0x4d0 mm/slab.c:3724
kmemdup+0x23/0x50 mm/util.c:128
kmemdup include/linux/fortify-string.h:304 [inline]
em28xx_duplicate_dev drivers/media/usb/em28xx/em28xx-cards.c:3690 [inline]
em28xx_usb_probe.cold+0x134a/0x258a drivers/media/usb/em28xx/em28xx-cards.c:4040
usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:517 [inline]
really_probe+0x245/0xcc0 drivers/base/dd.c:596
__driver_probe_device+0x338/0x4d0 drivers/base/dd.c:755
driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:785
__device_attach_driver+0x20b/0x2f0 drivers/base/dd.c:902
bus_for_each_drv+0x15f/0x1e0 drivers/base/bus.c:427
__device_attach+0x228/0x4a0 drivers/base/dd.c:973
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:487
device_add+0xb83/0x1e20 drivers/base/core.c:3405
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1353 [inline]
free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1403
free_unref_page_prepare mm/page_alloc.c:3325 [inline]
free_unref_page+0x19/0x690 mm/page_alloc.c:3420
skb_free_frag include/linux/skbuff.h:3135 [inline]
skb_free_head+0x96/0x110 net/core/skbuff.c:653
skb_release_data+0x6bc/0x810 net/core/skbuff.c:677
skb_release_all net/core/skbuff.c:742 [inline]
__kfree_skb+0x46/0x60 net/core/skbuff.c:756
__sk_defer_free_flush net/ipv4/tcp.c:1601 [inline]
sk_defer_free_flush include/net/tcp.h:1380 [inline]
tcp_recvmsg+0x1ca/0x610 net/ipv4/tcp.c:2577
inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:850
sock_recvmsg_nosec net/socket.c:948 [inline]
sock_recvmsg net/socket.c:966 [inline]
sock_recvmsg net/socket.c:962 [inline]
sock_read_iter+0x33c/0x470 net/socket.c:1039
call_read_iter include/linux/fs.h:2075 [inline]
new_sync_read+0x5c2/0x6e0 fs/read_write.c:401
vfs_read+0x49b/0x5e0 fs/read_write.c:482
ksys_read+0x1ee/0x250 fs/read_write.c:620
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:
ffff888027458100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888027458180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888027458200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888027458280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888027458300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
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syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Pavel Skripkin]

On 3/30/22 20:36, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 52d543b5497c Merge tag 'for-linus-5.17-1' of https://githu..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=17b804fb700000
> kernel config: https://syzkaller.appspot.com/x/.config?x=7094767cefc58fb9
> dashboard link: https://syzkaller.appspot.com/bug?extid=99d6c66dbbc484f50e1c
> 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=161c4739700000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16432d51700000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+99d6c6...@syzkaller.appspotmail.com
>
> em28xx 5-1:0.130: Config register raw data: 0xfffffffb
> em28xx 5-1:0.130: AC97 chip type couldn't be determined
> em28xx 5-1:0.130: No AC97 audio processor
> ==================================================================
> BUG: KASAN: use-after-free in __list_add_valid+0x93/0xa0 lib/list_debug.c:26
> Read of size 8 at addr ffff888027458250 by task kworker/1:1/40
>

Just want to warn anyone looking into this bug.

I came up with the fix, that passed syzbot testing and patch has been in
Linus' tree for couple of months: see commit 2c98b8a3458d ("media:
em28xx: add missing em28xx_close_extension").

After some time Maximilian sent a report about kernel hung bug caused by
my fix [1]. Just random hung caused by wrong reference counting
somewhere. No idea how to reproduce it locally or how to fix it.

I had to revert my fix, of course. That's why this bug appeared one more
time.

So, if you are going to send a fix, please, check that it does not have
same problem as mine.

Thanks


[1]
https://lore.kernel.org/all/6a72a37b-e972-187d...@elbmurf.de/



With regards,
Pavel Skripkin

[Hillf Danton]

On Wed, 30 Mar 2022 10:36:28 -0700

See if the uaf is due to ref imbalance.

Hillf

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 52d543b5497c

--- y/drivers/media/usb/em28xx/em28xx-cards.c
+++ x/drivers/media/usb/em28xx/em28xx-cards.c
@@ -4039,6 +4039,7 @@ static int em28xx_usb_probe(struct usb_i

if (dev->board.has_dual_ts && em28xx_duplicate_dev(dev) == 0) {
kref_init(&dev->dev_next->ref);
+ kref_get(&dev->dev_next->ref);

dev->dev_next->ts = SECONDARY_TS;
dev->dev_next->alt = -1;
--

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+99d6c6...@syzkaller.appspotmail.com

Tested on:

commit: 52d543b5 Merge tag 'for-linus-5.17-1' of https://githu..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/

kernel config: https://syzkaller.appspot.com/x/.config?x=7094767cefc58fb9
dashboard link: https://syzkaller.appspot.com/bug?extid=99d6c66dbbc484f50e1c
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=10453cd7700000

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