syzbot

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BUG: KASAN: use-after-free in v4l2_open+0x352/0x360 drivers/media/v4l2-core/v4l2-dev.c:432
Read of size 4 at addr ffff8880685049b0 by task v4l_id/4545

CPU: 1 PID: 4545 Comm: v4l_id Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 v4l2_open+0x352/0x360 drivers/media/v4l2-core/v4l2-dev.c:432
 chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3616 [inline]
 path_openat+0x26f5/0x2fa0 fs/namei.c:3750
 do_filp_open+0x1e2/0x410 fs/namei.c:3777
 do_sys_openat2+0x150/0x4b0 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f77134f4407
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:00007ffea5ecc7c0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f7713406880 RCX: 00007f77134f4407
RDX: 0000000000000000 RSI: 00007ffea5ecdf1d RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffea5ecca10 R14: 00007f7713c82000 R15: 000055681bc654d8
 </TASK>

The buggy address belongs to the page:
page:ffffea0001a14100 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x2 pfn:0x68504
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001999408 ffffea0001a0dc08 0000000000000000
raw: 0000000000000002 0000000000000002 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x102800(GFP_NOWAIT|__GFP_NOWARN|__GFP_HARDWALL), pid 7, ts 78129843256, free_ts 78129847736
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 stack_depot_save+0x342/0x440 lib/stackdepot.c:302
 kasan_save_stack mm/kasan/common.c:40 [inline]
 kasan_set_track+0x62/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 kobject_uevent_env+0x368/0x890 lib/kobject_uevent.c:640
 device_add+0x925/0x1000 drivers/base/core.c:3393
 cdev_device_add+0x1a4/0x340 fs/char_dev.c:549
 evdev_connect+0x34b/0x3f0 drivers/input/evdev.c:1386
 input_attach_handler drivers/input/input.c:1046 [inline]
 input_register_device+0xda7/0x1140 drivers/input/input.c:2429
 em28xx_register_snapshot_button+0x2d8/0x460 drivers/media/usb/em28xx/em28xx-input.c:610
 em28xx_init_buttons drivers/media/usb/em28xx/em28xx-input.c:648 [inline]
 em28xx_ir_init+0x625/0x1db0 drivers/media/usb/em28xx/em28xx-input.c:715
 em28xx_init_extension+0x118/0x1b0 drivers/media/usb/em28xx/em28xx-core.c:1126
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 stack_depot_save+0x418/0x440 lib/stackdepot.c:335
 kasan_save_stack mm/kasan/common.c:40 [inline]
 kasan_set_track+0x62/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 kobject_uevent_env+0x368/0x890 lib/kobject_uevent.c:640
 device_add+0x925/0x1000 drivers/base/core.c:3393
 cdev_device_add+0x1a4/0x340 fs/char_dev.c:549
 evdev_connect+0x34b/0x3f0 drivers/input/evdev.c:1386
 input_attach_handler drivers/input/input.c:1046 [inline]
 input_register_device+0xda7/0x1140 drivers/input/input.c:2429
 em28xx_register_snapshot_button+0x2d8/0x460 drivers/media/usb/em28xx/em28xx-input.c:610
 em28xx_init_buttons drivers/media/usb/em28xx/em28xx-input.c:648 [inline]
 em28xx_ir_init+0x625/0x1db0 drivers/media/usb/em28xx/em28xx-input.c:715
 em28xx_init_extension+0x118/0x1b0 drivers/media/usb/em28xx/em28xx-core.c:1126

Memory state around the buggy address:
 ffff888068504880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888068504900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888068504980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                     ^
 ffff888068504a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888068504a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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