================================================================== BUG: KASAN: use-after-free in dvb_device_open+0xd4/0x38c drivers/media/dvb-core/dvbdev.c:99 Read of size 8 at addr ffff0000d31a8e18 by task syz.4.184/5168 CPU: 1 PID: 5168 Comm: syz.4.184 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 print_address_description+0x88/0x218 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:420 kasan_report+0xa8/0xfc mm/kasan/report.c:524 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351 dvb_device_open+0xd4/0x38c drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x3d0/0x51c fs/char_dev.c:414 do_dentry_open+0x738/0xf8c fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3677 [inline] path_openat+0x1fc0/0x27a0 fs/namei.c:3834 do_filp_open+0x198/0x38c fs/namei.c:3861 do_sys_openat2+0x134/0x3fc fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Allocated by task 1: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:53 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384 kasan_kmalloc include/linux/kasan.h:211 [inline] kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] dvb_register_device+0x1a4/0x1800 drivers/media/dvb-core/dvbdev.c:478 dvb_register_frontend+0x4d0/0x750 drivers/media/dvb-core/dvb_frontend.c:3035 vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:438 [inline] vidtv_bridge_probe+0x9cc/0xe38 drivers/media/test-drivers/vidtv/vidtv_bridge.c:510 platform_probe+0x148/0x1c8 drivers/base/platform.c:1400 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x3a0/0xac4 drivers/base/dd.c:638 __driver_probe_device+0x1c8/0x368 drivers/base/dd.c:804 driver_probe_device+0x78/0x324 drivers/base/dd.c:834 __driver_attach+0x3bc/0x614 drivers/base/dd.c:1220 bus_for_each_dev+0x148/0x1d0 drivers/base/bus.c:303 driver_attach+0x50/0x60 drivers/base/dd.c:1237 bus_add_driver+0x2c0/0x518 drivers/base/bus.c:620 driver_register+0x200/0x37c drivers/base/driver.c:246 __platform_driver_register+0x70/0x84 drivers/base/platform.c:867 vidtv_bridge_init+0x58/0x98 drivers/media/test-drivers/vidtv/vidtv_bridge.c:604 do_one_initcall+0x278/0x9f0 init/main.c:1271 do_initcall_level+0x158/0x214 init/main.c:1344 do_initcalls+0x58/0xac init/main.c:1360 do_basic_setup+0x8c/0xa0 init/main.c:1379 kernel_init_freeable+0x35c/0x4f0 init/main.c:1599 kernel_init+0x24/0x1d8 init/main.c:1487 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850 The buggy address belongs to the object at ffff0000d31a8e00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of 256-byte region [ffff0000d31a8e00, ffff0000d31a8f00) The buggy address belongs to the physical page: page:000000000cae8d04 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0000d31a8400 pfn:0x1131a8 head:000000000cae8d04 order:1 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 fffffc00036b9888 fffffc00034b9688 ffff0000c0002480 raw: ffff0000d31a8400 000000000010000e 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d31a8d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000d31a8d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000d31a8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000d31a8e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d31a8f00: 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: CPU: 0 PID: 5168 at lib/refcount.c:25 refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 5168 Comm: syz.4.184 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026 pstate: 62400005 (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 : ffff800022587620 x29: ffff800022587620 x28: 1fffe0001970dd98 x27: 1fffe0001b2f3055 x26: ffff0000d97982a8 x25: ffff0000d328e000 x24: dfff800000000000 x23: 0000000000000000 x22: ffff0000d31a8e10 x21: ffff0000cb86ec90 x20: ffff0000d31a8e10 x19: ffff800018dfb000 x18: 1fffe00033c1877e x17: ffff80001641d000 x16: ffff800008043a58 x15: 0000000040000000 x14: 0000000000000001 x13: 1fffe00033c1ae70 x12: 0000000000000000 x11: ff00800008048d3c x10: 0000000040000002 x9 : 0e717f79fe652d00 x8 : 0e717f79fe652d00 x7 : ffff800011d2c160 x6 : ffff80000825ab2c x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000 x2 : ffff8000225871e0 x1 : 0000000000000000 x0 : ffff80000825abc0 Call trace: refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25 __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] dvb_device_get drivers/media/dvb-core/dvbdev.c:631 [inline] dvb_device_open+0x32c/0x38c drivers/media/dvb-core/dvbdev.c:106 chrdev_open+0x3d0/0x51c fs/char_dev.c:414 do_dentry_open+0x738/0xf8c fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3677 [inline] path_openat+0x1fc0/0x27a0 fs/namei.c:3834 do_filp_open+0x198/0x38c fs/namei.c:3861 do_sys_openat2+0x134/0x3fc fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 irq event stamp: 765 hardirqs last enabled at (765): [] raw_spin_rq_unlock_irq kernel/sched/sched.h:1374 [inline] hardirqs last enabled at (765): [] finish_lock_switch+0xb0/0x1c8 kernel/sched/core.c:5005 hardirqs last disabled at (764): [] __schedule+0x294/0x1a6c kernel/sched/core.c:6461 softirqs last enabled at (212): [] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 softirqs last disabled at (210): [] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19 ---[ end trace 0000000000000000 ]---