================================================================== 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 ffff0000cbb89c18 by task syz.2.1331/10834 CPU: 0 UID: 0 PID: 10834 Comm: syz.2.1331 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026 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+0x5c4/0xfc0 fs/open.c:947 vfs_open+0x44/0x2dc fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x21fc/0x2a60 fs/namei.c:4859 do_file_open+0x1c8/0x2e8 fs/namei.c:4888 do_sys_openat2+0x114/0x1e8 fs/open.c:1368 do_sys_open+0xb0/0xe0 fs/open.c:1374 __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __arm64_sys_openat+0xa0/0xbc fs/open.c:1385 __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+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 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+0x44/0x54 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+0x2e8/0x5ec mm/slub.c:5515 _kmalloc_noprof include/linux/slab.h:969 [inline] _kzalloc_noprof include/linux/slab.h:1290 [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:3051 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:1439 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:927 vidtv_bridge_init+0x4c/0x74 drivers/media/test-drivers/vidtv/vidtv_bridge.c:602 do_one_initcall+0x274/0xc38 init/main.c:1347 do_initcall_level+0x12c/0x1c4 init/main.c:1409 do_initcalls+0x70/0xd0 init/main.c:1425 do_basic_setup+0x7c/0x90 init/main.c:1445 kernel_init_freeable+0x268/0x3a8 init/main.c:1658 kernel_init+0x24/0x1dc init/main.c:1548 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842 Freed by task 10660: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:78 kasan_save_free_info+0x58/0x70 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:2705 [inline] slab_free mm/slub.c:6405 [inline] kfree+0x188/0x690 mm/slub.c:6720 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+0x5c4/0xfc0 fs/open.c:947 vfs_open+0x44/0x2dc fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x21fc/0x2a60 fs/namei.c:4859 do_file_open+0x1c8/0x2e8 fs/namei.c:4888 do_sys_openat2+0x114/0x1e8 fs/open.c:1368 do_sys_open+0xb0/0xe0 fs/open.c:1374 __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __arm64_sys_openat+0xa0/0xbc fs/open.c:1385 __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+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 The buggy address belongs to the object at ffff0000cbb89c00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of freed 256-byte region [ffff0000cbb89c00, ffff0000cbb89d00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10bb88 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 0000000800100010 00000000f5000000 0000000000000000 head: 05ffc00000000040 ffff0000c0001b40 dead000000000100 dead000000000122 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 05ffc00000000001 fffffdffc32ee201 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000cbb89b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000cbb89b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000cbb89c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000cbb89c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000cbb89d00: 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.2.1331/10834 Modules linked in: CPU: 0 UID: 0 PID: 10834 Comm: syz.2.1331 Tainted: G B L syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026 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 : ffff800095417640 x29: ffff800095417640 x28: dfff800000000000 x27: 1fffe0001ab20c41 x26: dfff800000000000 x25: ffff700012a82edc x24: dfff800000000000 x23: ffff80008742cca8 x22: ffff0000cbc2dc00 x21: ffff0000cbb89c00 x20: ffff0000cbb89c10 x19: ffff80008a116000 x18: 0000000000000000 x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d x14: 3d3d3d3d3d3d3d3d x13: 0000000000000001 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000080000 x9 : bc11838d3343b600 x8 : bc11838d3343b600 x7 : 0000000000000000 x6 : ffff80008048ce60 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f7010 x2 : 0000000100000000 x1 : ffff0000dbb99d40 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+0x5c4/0xfc0 fs/open.c:947 vfs_open+0x44/0x2dc fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x21fc/0x2a60 fs/namei.c:4859 do_file_open+0x1c8/0x2e8 fs/namei.c:4888 do_sys_openat2+0x114/0x1e8 fs/open.c:1368 do_sys_open+0xb0/0xe0 fs/open.c:1374 __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __arm64_sys_openat+0xa0/0xbc fs/open.c:1385 __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+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 irq event stamp: 437 hardirqs last enabled at (437): [] irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:507 [inline] hardirqs last enabled at (437): [] arm64_exit_to_kernel_mode+0x80/0x94 arch/arm64/kernel/entry-common.c:62 hardirqs last disabled at (436): [] __el1_irq arch/arm64/kernel/entry-common.c:506 [inline] hardirqs last disabled at (436): [] el1_interrupt+0x28/0x60 arch/arm64/kernel/entry-common.c:522 softirqs last enabled at (412): [] local_bh_enable include/linux/bottom_half.h:33 [inline] softirqs last enabled at (412): [] put_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:251 [inline] softirqs last enabled at (412): [] do_sve_acc+0x32c/0x4b8 arch/arm64/kernel/fpsimd.c:1349 softirqs last disabled at (410): [] local_bh_disable include/linux/bottom_half.h:20 [inline] softirqs last disabled at (410): [] get_cpu_fpsimd_context arch/arm64/kernel/fpsimd.c:234 [inline] softirqs last disabled at (410): [] do_sve_acc+0x10c/0x4b8 arch/arm64/kernel/fpsimd.c:1325 ---[ end trace 0000000000000000 ]---