================================================================== BUG: KASAN: slab-use-after-free in dvb_device_open+0xd0/0x254 drivers/media/dvb-core/dvbdev.c:99 Read of size 8 at addr ffff0000cc0a0c18 by task syz.9.1142/9303 CP CPU: 1 UID: 0 PID: 9303 Comm: syz.9.1142 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_address_description+0xb0/0x238 mm/kasan/report.c:378 print_report+0x68/0x84 mm/kasan/report.c:482 kasan_report+0x8c/0xc4 mm/kasan/report.c:595 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 dvb_device_open+0xd0/0x254 drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x398/0x3e8 fs/char_dev.c:411 do_dentry_open+0x5c4/0xfbc fs/open.c:996 vfs_open+0x44/0x2dc fs/open.c:1101 do_open fs/namei.c:4866 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5029 do_file_open+0x1c8/0x2e8 fs/namei.c:5058 do_sys_openat2+0x114/0x1e8 fs/open.c:1417 do_sys_open+0xb0/0xe0 fs/open.c:1423 __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __arm64_sys_openat+0xa8/0xc4 fs/open.c:1434 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606 Allocated by task 1: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:78 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:570 poison_kmalloc_redzone mm/kasan/common.c:409 [inline] __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:426 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x2f4/0x5fc mm/slub.c:5563 _kmalloc_noprof include/linux/slab.h:991 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] dvb_register_device+0x1a4/0x16e0 drivers/media/dvb-core/dvbdev.c:472 dvb_register_frontend+0x474/0x6d0 drivers/media/dvb-core/dvb_frontend.c:3074 vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:438 [inline] vidtv_bridge_probe+0x5a4/0xa58 drivers/media/test-drivers/vidtv/vidtv_bridge.c:510 platform_probe+0x100/0x1a4 drivers/base/platform.c:1507 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x29c/0x800 drivers/base/dd.c:706 __driver_probe_device+0x1e0/0x350 drivers/base/dd.c:868 driver_probe_device+0x6c/0x19c drivers/base/dd.c:898 __driver_attach+0x168/0x384 drivers/base/dd.c:1292 bus_for_each_dev+0x128/0x1b4 drivers/base/bus.c:383 driver_attach+0x50/0x60 drivers/base/dd.c:1310 bus_add_driver+0x208/0x500 drivers/base/bus.c:763 driver_register+0x220/0x310 drivers/base/driver.c:174 __platform_driver_register+0x90/0xa4 drivers/base/platform.c:995 vidtv_bridge_init+0x4c/0x74 drivers/media/test-drivers/vidtv/vidtv_bridge.c:602 do_one_initcall+0x274/0x9f8 init/main.c:1362 do_initcall_level+0x12c/0x1c4 init/main.c:1424 do_initcalls+0x70/0xd0 init/main.c:1440 do_basic_setup+0x7c/0x90 init/main.c:1460 kernel_init_freeable+0x258/0x398 init/main.c:1675 kernel_init+0x28/0x1e0 init/main.c:1565 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:854 Freed by task 9123: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:78 kasan_save_free_info+0x54/0x6c mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:264 [inline] __kasan_slab_free+0x74/0xa4 mm/kasan/common.c:296 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6509 [inline] kfree+0x188/0x658 mm/slub.c:6802 dvb_free_device drivers/media/dvb-core/dvbdev.c:616 [inline] kref_put include/linux/kref.h:65 [inline] dvb_device_put+0x64/0xd0 drivers/media/dvb-core/dvbdev.c:629 dvb_device_open+0x23c/0x254 drivers/media/dvb-core/dvbdev.c:113 chrdev_open+0x398/0x3e8 fs/char_dev.c:411 do_dentry_open+0x5c4/0xfbc fs/open.c:996 vfs_open+0x44/0x2dc fs/open.c:1101 do_open fs/namei.c:4866 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5029 do_file_open+0x1c8/0x2e8 fs/namei.c:5058 do_sys_openat2+0x114/0x1e8 fs/open.c:1417 do_sys_open+0xb0/0xe0 fs/open.c:1423 __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __arm64_sys_openat+0xa8/0xc4 fs/open.c:1434 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606 The buggy address belongs to the object at ffff0000cc0a0c00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of freed 256-byte region [ffff0000cc0a0c00, ffff0000cc0a0d00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10c0a0 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 05ffc00000000040 ffff0000c0001b40 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 05ffc00000000040 ffff0000c0001b40 dead000000000100 dead000000000122 head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 head: 05ffc00000000001 fffffdffc3302801 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000cc0a0b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000cc0a0b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000cc0a0c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000cc0a0c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000cc0a0d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25, CPU#0: syz.9.1142/9303 Modules linked in: CPU: 0 UID: 0 PID: 9303 Comm: syz.9.1142 Tainted: G B L syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026 pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25 lr : refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25 sp : ffff800095267700 x29: ffff800095267700 x28: dfff800000000000 x27: 1fffe00019efab89 x26: dfff800000000000 x25: ffff700012a4cef4 x24: dfff800000000000 x23: ffff8000873f5d48 x22: ffff0000cb48b000 x21: ffff0000cc0a0c00 x20: ffff0000cc0a0c10 x19: ffff80008ae12000 x18: 1fffe000349f7028 x17: 0000000000000003 x16: ffff800089797000 x15: 0000000000000000 x14: 0000000000001af8 x13: 0000000000000001 x12: 0000000000000003 x11: 0000000000000000 x10: 0000000000080000 x9 : d1b8bed7095caa00 x8 : d1b8bed7095caa00 x7 : 0000000000000000 x6 : ffff800080483084 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f3d68 x2 : 0000000100000000 x1 : ffff0000ca693b00 x0 : 0000000000000001 Call trace: refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25 (P) __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:366 [inline] refcount_inc include/linux/refcount.h:383 [inline] kref_get include/linux/kref.h:45 [inline] dvb_device_get+0x9c/0xc0 drivers/media/dvb-core/dvbdev.c:621 dvb_device_open+0x100/0x254 drivers/media/dvb-core/dvbdev.c:106 chrdev_open+0x398/0x3e8 fs/char_dev.c:411 do_dentry_open+0x5c4/0xfbc fs/open.c:996 vfs_open+0x44/0x2dc fs/open.c:1101 do_open fs/namei.c:4866 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5029 do_file_open+0x1c8/0x2e8 fs/namei.c:5058 do_sys_openat2+0x114/0x1e8 fs/open.c:1417 do_sys_open+0xb0/0xe0 fs/open.c:1423 __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __arm64_sys_openat+0xa8/0xc4 fs/open.c:1434 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:796 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:815 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606 irq event stamp: 85 hardirqs last enabled at (85): [] raw_spin_rq_unlock_irq kernel/sched/sched.h:1697 [inline] hardirqs last enabled at (85): [] finish_lock_switch kernel/sched/core.c:5264 [inline] hardirqs last enabled at (85): [] finish_task_switch+0x234/0x858 kernel/sched/core.c:5382 hardirqs last disabled at (84): [] __schedule+0x2f8/0x2b00 kernel/sched/core.c:7137 softirqs last enabled at (28): [] local_bh_enable include/linux/bottom_half.h:33 [inline] softirqs last enabled at (28): [] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline] softirqs last enabled at (28): [] do_sve_acc+0x3ac/0x56c arch/arm64/kernel/fpsimd.c:1333 softirqs last disabled at (26): [] local_bh_disable include/linux/bottom_half.h:20 [inline] softirqs last disabled at (26): [] get_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:234 [inline] softirqs last disabled at (26): [] do_sve_acc+0x104/0x56c arch/arm64/kernel/fpsimd.c:1308 ---[ end trace 0000000000000000 ]---