[syzbot] [media?] [usb?] KASAN: slab-use-after-free Read in v4l2_release (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d245acc1e88 Merge tag 'char-misc-6.17-rc3' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f37062580000
kernel config: https://syzkaller.appspot.com/x/.config?x=292f3bc9f654adeb
dashboard link: https://syzkaller.appspot.com/bug?extid=a658d41cf8564471775e
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c267bc580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a8c862580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/924cb94b3bad/disk-8d245acc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/df04a64e8404/vmlinux-8d245acc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/92335877cbf3/bzImage-8d245acc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a658d4...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in v4l2_release+0xbd/0x3b0 drivers/media/v4l2-core/v4l2-dev.c:455
Read of size 8 at addr ffff88803380c0c8 by task v4l_id/7890

CPU: 0 UID: 0 PID: 7890 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
v4l2_release+0xbd/0x3b0 drivers/media/v4l2-core/v4l2-dev.c:455
__fput+0x44c/0xa70 fs/file_table.c:468
fput_close_sync+0x119/0x200 fs/file_table.c:573
__do_sys_close fs/open.c:1587 [inline]
__se_sys_close fs/open.c:1572 [inline]
__x64_sys_close+0x7f/0x110 fs/open.c:1572
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe6c60a7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff98873b40 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007fe6c675e880 RCX: 00007fe6c60a7407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fe6c675e6e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
R13: 00007fff98873d70 R14: 00007fe6c6863000 R15: 0000561c633154d8
</TASK>

Allocated by task 6061:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4396
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
hackrf_probe+0xda/0x1360 drivers/media/usb/hackrf/hackrf.c:1351
usb_probe_interface+0x668/0xc30 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x26d/0x9e0 drivers/base/dd.c:659
__driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
__device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:462
__device_attach+0x2b8/0x400 drivers/base/dd.c:1031
bus_probe_device+0x185/0x260 drivers/base/bus.c:537
device_add+0x7b6/0xb50 drivers/base/core.c:3689
usb_set_configuration+0x1a87/0x20e0 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
usb_probe_device+0x1c4/0x390 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x26d/0x9e0 drivers/base/dd.c:659
__driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
__device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:462
__device_attach+0x2b8/0x400 drivers/base/dd.c:1031
bus_probe_device+0x185/0x260 drivers/base/bus.c:537
device_add+0x7b6/0xb50 drivers/base/core.c:3689
usb_new_device+0xa39/0x16f0 drivers/usb/core/hub.c:2694
hub_port_connect drivers/usb/core/hub.c:5566 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
port_event drivers/usb/core/hub.c:5870 [inline]
hub_event+0x2958/0x4a20 drivers/usb/core/hub.c:5952
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6061:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:243 [inline]
__kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2417 [inline]
slab_free mm/slub.c:4680 [inline]
kfree+0x18e/0x440 mm/slub.c:4879
hackrf_probe+0xd98/0x1360 drivers/media/usb/hackrf/hackrf.c:1523
usb_probe_interface+0x668/0xc30 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x26d/0x9e0 drivers/base/dd.c:659
__driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
__device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:462
__device_attach+0x2b8/0x400 drivers/base/dd.c:1031
bus_probe_device+0x185/0x260 drivers/base/bus.c:537
device_add+0x7b6/0xb50 drivers/base/core.c:3689
usb_set_configuration+0x1a87/0x20e0 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
usb_probe_device+0x1c4/0x390 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x26d/0x9e0 drivers/base/dd.c:659
__driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
__device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:462
__device_attach+0x2b8/0x400 drivers/base/dd.c:1031
bus_probe_device+0x185/0x260 drivers/base/bus.c:537
device_add+0x7b6/0xb50 drivers/base/core.c:3689
usb_new_device+0xa39/0x16f0 drivers/usb/core/hub.c:2694
hub_port_connect drivers/usb/core/hub.c:5566 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
port_event drivers/usb/core/hub.c:5870 [inline]
hub_event+0x2958/0x4a20 drivers/usb/core/hub.c:5952
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88803380c000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 200 bytes inside of
freed 8192-byte region [ffff88803380c000, ffff88803380e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33808
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a442280 ffffea00008ec000 dead000000000006
raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a442280 ffffea00008ec000 dead000000000006
head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000ce0201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 25007805576, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
prep_new_page mm/page_alloc.c:1859 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
alloc_slab_page mm/slub.c:2487 [inline]
allocate_slab+0x8a/0x370 mm/slub.c:2655
new_slab mm/slub.c:2709 [inline]
___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
__slab_alloc mm/slub.c:3981 [inline]
__slab_alloc_node mm/slub.c:4056 [inline]
slab_alloc_node mm/slub.c:4217 [inline]
__do_kmalloc_node mm/slub.c:4364 [inline]
__kmalloc_noprof+0x305/0x4f0 mm/slub.c:4377
kmalloc_noprof include/linux/slab.h:909 [inline]
kmalloc_array_noprof include/linux/slab.h:948 [inline]
mb_cache_create+0x15f/0x540 fs/mbcache.c:368
__ext4_fill_super fs/ext4/super.c:5447 [inline]
ext4_fill_super+0x40a9/0x6090 fs/ext4/super.c:5728
get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1692
vfs_get_tree+0x92/0x2b0 fs/super.c:1815
do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808
init_mount+0xbb/0x100 fs/init.c:25
do_mount_root+0xf4/0x260 init/do_mounts.c:165
mount_root_generic+0x198/0x350 init/do_mounts.c:204
prepare_namespace+0x71/0xa0 init/do_mounts.c:491
page_owner free stack trace missing

Memory state around the buggy address:
ffff88803380bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88803380c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88803380c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88803380c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88803380c180: 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.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Hillf Danton]

> Date: Sat, 23 Aug 2025 23:17:26 -0700 [thread overview]

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 8d245acc1e88 Merge tag 'char-misc-6.17-rc3' of git://git.k..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15f37062580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=292f3bc9f654adeb
> dashboard link: https://syzkaller.appspot.com/bug?extid=a658d41cf8564471775e
> compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c267bc580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a8c862580000

#syz test

--- x/drivers/media/usb/hackrf/hackrf.c
+++ y/drivers/media/usb/hackrf/hackrf.c
@@ -1345,7 +1345,7 @@ static int hackrf_probe(struct usb_inter
const struct usb_device_id *id)
{
struct hackrf_dev *dev;
- int ret;
+ int ret, registered = 0;
u8 u8tmp, buf[BUF_SIZE];

dev = kzalloc(sizeof(*dev), GFP_KERNEL);
@@ -1487,6 +1487,7 @@ static int hackrf_probe(struct usb_inter
"Failed to register as video device (%d)\n", ret);
goto err_v4l2_device_unregister;
}
+ registered++;
dev_info(dev->dev, "Registered as %s\n",
video_device_node_name(&dev->rx_vdev));

@@ -1520,7 +1521,8 @@ err_v4l2_ctrl_handler_free_tx:
err_v4l2_ctrl_handler_free_rx:
v4l2_ctrl_handler_free(&dev->rx_ctrl_handler);
err_kfree:
- kfree(dev);
+ if (!registered)
+ kfree(dev);
err:
dev_dbg(&intf->dev, "failed=%d\n", ret);
return ret;
--

[syzbot]

Hello,

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

Reported-by: syzbot+a658d4...@syzkaller.appspotmail.com
Tested-by: syzbot+a658d4...@syzkaller.appspotmail.com

Tested on:

commit: 8d245acc Merge tag 'char-misc-6.17-rc3' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c0ba34580000

kernel config: https://syzkaller.appspot.com/x/.config?x=292f3bc9f654adeb
dashboard link: https://syzkaller.appspot.com/bug?extid=a658d41cf8564471775e
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

patch: https://syzkaller.appspot.com/x/patch.diff?x=12ef4ef0580000

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