================================================================== BUG: KASAN: use-after-free in dvb_device_open+0xd4/0x388 drivers/media/dvb-core/dvbdev.c:99 Read of size 8 at addr ffff0000ca087818 by task syz.3.67/4651 CPU: 1 PID: 4651 Comm: syz.3.67 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: dump_backtrace+0x1c0/0x1ec 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+0xd4/0x388 drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x3d4/0x518 fs/char_dev.c:414 do_dentry_open+0x72c/0xf98 fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3634 [inline] path_openat+0x1f8c/0x26bc fs/namei.c:3791 do_filp_open+0x194/0x384 fs/namei.c:3818 do_sys_openat2+0x134/0x3f4 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+0x118/0x14c fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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+0x1a0/0x17a8 drivers/media/dvb-core/dvbdev.c:478 dvb_register_frontend+0x4c0/0x720 drivers/media/dvb-core/dvb_frontend.c:3035 vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:436 [inline] vidtv_bridge_probe+0x9ac/0xe34 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508 platform_probe+0x13c/0x1b4 drivers/base/platform.c:1400 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x39c/0xacc drivers/base/dd.c:639 __driver_probe_device+0x180/0x310 drivers/base/dd.c:785 driver_probe_device+0x78/0x324 drivers/base/dd.c:815 __driver_attach+0x3bc/0x60c drivers/base/dd.c:1201 bus_for_each_dev+0x148/0x1d0 drivers/base/bus.c:303 driver_attach+0x4c/0x5c drivers/base/dd.c:1218 bus_add_driver+0x2d8/0x554 drivers/base/bus.c:620 driver_register+0x200/0x378 drivers/base/driver.c:246 __platform_driver_register+0x6c/0x80 drivers/base/platform.c:867 vidtv_bridge_init+0x4c/0x8c drivers/media/test-drivers/vidtv/vidtv_bridge.c:600 do_one_initcall+0x278/0x9e0 init/main.c:1310 do_initcall_level+0x154/0x214 init/main.c:1383 do_initcalls+0x58/0xac init/main.c:1399 do_basic_setup+0x8c/0xa0 init/main.c:1418 kernel_init_freeable+0x35c/0x4f0 init/main.c:1638 kernel_init+0x24/0x1d8 init/main.c:1526 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850 Freed by task 4580: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:53 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xbc/0x218 mm/slub.c:3700 kfree+0xd0/0x1a8 mm/slab_common.c:988 dvb_free_device drivers/media/dvb-core/dvbdev.c:625 [inline] kref_put include/linux/kref.h:65 [inline] dvb_device_put drivers/media/dvb-core/dvbdev.c:640 [inline] dvb_device_open+0x2dc/0x388 drivers/media/dvb-core/dvbdev.c:113 chrdev_open+0x3d4/0x518 fs/char_dev.c:414 do_dentry_open+0x72c/0xf98 fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3634 [inline] path_openat+0x1f8c/0x26bc fs/namei.c:3791 do_filp_open+0x194/0x384 fs/namei.c:3818 do_sys_openat2+0x134/0x3f4 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+0x118/0x14c fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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 The buggy address belongs to the object at ffff0000ca087800 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of 256-byte region [ffff0000ca087800, ffff0000ca087900) The buggy address belongs to the physical page: page:00000000fffa661f refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0000ca087600 pfn:0x10a086 head:00000000fffa661f order:1 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 fffffc00034aca08 fffffc00034ac488 ffff0000c0002480 raw: ffff0000ca087600 0000000000100007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000ca087700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000ca087780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000ca087800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000ca087880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000ca087900: 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: 1 PID: 4651 at lib/refcount.c:25 refcount_warn_saturate+0x134/0x1f8 lib/refcount.c:25 Modules linked in: CPU: 1 PID: 4651 Comm: syz.3.67 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 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 : ffff8000219075c0 x29: ffff8000219075c0 x28: ffff0000ccb06a28 x27: dfff800000000000 x26: ffff0000d3122c00 x25: dfff800000000000 x24: 1fffe00019410f03 x23: 0000000000000000 x22: ffff0000ca087810 x21: ffff0000d2a84060 x20: ffff0000ca087810 x19: ffff800017bd9000 x18: ffff800011b8bf60 x17: 1fffe00033eac97e x16: ffff80000804309c x15: 0000000040000000 x14: 0000000000000001 x13: 1fffe00033eaf030 x12: 0000000000ff0100 x11: ff00800008048348 x10: 0000000040000002 x9 : e990bdc4ee3ffe00 x8 : e990bdc4ee3ffe00 x7 : 0000000000000004 x6 : ffff80000825796c x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000 x2 : ffff800021907160 x1 : 0000000000000000 x0 : ffff800008257a00 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+0x328/0x388 drivers/media/dvb-core/dvbdev.c:106 chrdev_open+0x3d4/0x518 fs/char_dev.c:414 do_dentry_open+0x72c/0xf98 fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3634 [inline] path_openat+0x1f8c/0x26bc fs/namei.c:3791 do_filp_open+0x194/0x384 fs/namei.c:3818 do_sys_openat2+0x134/0x3f4 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+0x118/0x14c fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 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: 677 hardirqs last enabled at (677): [] raw_spin_rq_unlock_irq kernel/sched/sched.h:1374 [inline] hardirqs last enabled at (677): [] finish_lock_switch+0xb0/0x1c4 kernel/sched/core.c:5004 hardirqs last disabled at (676): [] __schedule+0x298/0x1b0c kernel/sched/core.c:6460 softirqs last enabled at (478): [] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32 softirqs last disabled at (476): [] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19 ---[ end trace 0000000000000000 ]---