================================================================== 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 ffff0000cb555e18 by task syz.7.710/9406 CPU: 1 UID: 0 PID: 9406 Comm: syz.7.710 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 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:4837 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5000 do_file_open+0x1c8/0x2e8 fs/namei.c:5029 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:398 [inline] __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:415 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 9391: 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:253 [inline] __kasan_slab_free+0x74/0xa4 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6508 [inline] kfree+0x188/0x658 mm/slub.c:6801 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:4837 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5000 do_file_open+0x1c8/0x2e8 fs/namei.c:5029 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 ffff0000cb555e00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of freed 256-byte region [ffff0000cb555e00, ffff0000cb555f00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10b554 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 fffffdffc32d5501 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000cb555d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000cb555d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000cb555e00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000cb555e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000cb555f00: 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#1: syz.7.710/9406 Modules linked in: CPU: 1 UID: 0 PID: 9406 Comm: syz.7.710 Tainted: G B syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 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 : ffff800093917700 x29: ffff800093917700 x28: dfff800000000000 x27: 1fffe0001b2e1e39 x26: dfff800000000000 x25: ffff700012722ef4 x24: dfff800000000000 x23: ffff8000873d1f28 x22: ffff0000cb7f4800 x21: ffff0000cb555e00 x20: ffff0000cb555e10 x19: ffff80008a0cf000 x18: 0000000000000000 x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d x14: 0000000000001e19 x13: 0000000000000001 x12: 0000000000000003 x11: 0000000000000000 x10: 0000000000080000 x9 : 6ac78b189f797400 x8 : 6ac78b189f797400 x7 : 0000000000000000 x6 : ffff8000804823d8 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f3e90 x2 : 0000000100000000 x1 : ffff0000c4b7d880 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:4837 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5000 do_file_open+0x1c8/0x2e8 fs/namei.c:5029 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: 341 hardirqs last enabled at (341): [] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:210 [inline] hardirqs last enabled at (341): [] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:221 hardirqs last disabled at (340): [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:153 [inline] hardirqs last disabled at (340): [] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:181 softirqs last enabled at (318): [] local_bh_enable include/linux/bottom_half.h:33 [inline] softirqs last enabled at (318): [] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline] softirqs last enabled at (318): [] do_sve_acc+0x32c/0x4b8 arch/arm64/kernel/fpsimd.c:1332 softirqs last disabled at (316): [] local_bh_disable include/linux/bottom_half.h:20 [inline] softirqs last disabled at (316): [] get_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:234 [inline] softirqs last disabled at (316): [] do_sve_acc+0x10c/0x4b8 arch/arm64/kernel/fpsimd.c:1308 ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28, CPU#1: syz.7.710/9406 Modules linked in: CPU: 1 UID: 0 PID: 9406 Comm: syz.7.710 Tainted: G B W syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE, [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 lr : refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 sp : ffff8000939175b0 x29: ffff8000939175b0 x28: ffff0000cb1ca800 x27: ffff0000cb555e00 x26: ffff0000cae70308 x25: dfff800000000000 x24: ffff0000cabbc180 x23: 00000000fffffffc x22: 1fffe000196aabc7 x21: 00000000c0000000 x20: ffff0000cb555e10 x19: ffff80008a0cf000 x18: 0000000000000000 x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d x14: 0000000000001e66 x13: 0000000000000001 x12: 0000000000000003 x11: 0000000000000000 x10: 0000000000080000 x9 : 6ac78b189f797400 x8 : 6ac78b189f797400 x7 : 0000000000000000 x6 : ffff8000804823d8 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f3e90 x2 : 0000000100000000 x1 : ffff0000c4b7d880 x0 : 0000000000000001 Call trace: refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 (P) __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] kref_put include/linux/kref.h:64 [inline] dvb_device_put+0xac/0xd0 drivers/media/dvb-core/dvbdev.c:629 dvb_generic_release+0xec/0x158 drivers/media/dvb-core/dvbdev.c:169 __dvb_frontend_open+0x5c4/0xa34 drivers/media/dvb-core/dvb_frontend.c:2837 dvb_frontend_open+0x19c/0x70c drivers/media/dvb-core/dvb_frontend.c:2884 dvb_device_open+0x1f8/0x254 drivers/media/dvb-core/dvbdev.c:109 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:4837 [inline] path_openat+0x1084/0x18f0 fs/namei.c:5000 do_file_open+0x1c8/0x2e8 fs/namei.c:5029 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: 341 hardirqs last enabled at (341): [] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:210 [inline] hardirqs last enabled at (341): [] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:221 hardirqs last disabled at (340): [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:153 [inline] hardirqs last disabled at (340): [] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:181 softirqs last enabled at (318): [] local_bh_enable include/linux/bottom_half.h:33 [inline] softirqs last enabled at (318): [] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline] softirqs last enabled at (318): [] do_sve_acc+0x32c/0x4b8 arch/arm64/kernel/fpsimd.c:1332 softirqs last disabled at (316): [] local_bh_disable include/linux/bottom_half.h:20 [inline] softirqs last disabled at (316): [] get_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:234 [inline] softirqs last disabled at (316): [] do_sve_acc+0x10c/0x4b8 arch/arm64/kernel/fpsimd.c:1308 ---[ end trace 0000000000000000 ]---