================================================================== BUG: KASAN: slab-use-after-free in dvb_frontend_release+0x40a/0x4d0 drivers/media/dvb-core/dvb_frontend.c:2916 Read of size 4 at addr ffff88802cf6663c by task syz.2.6350/28807 CPU: 1 UID: 0 PID: 28807 Comm: syz.2.6350 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 dvb_frontend_release+0x40a/0x4d0 drivers/media/dvb-core/dvb_frontend.c:2916 __fput+0x44f/0xa60 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x193/0x680 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] __do_fast_syscall_32+0x45b/0x6f0 arch/x86/entry/syscall_32.c:310 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf70bf01c Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8 RSP: 002b:00000000f75dfb1c EFLAGS: 00000206 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 000000000000001e RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 1: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] dvb_register_device+0x2fd/0x21e0 drivers/media/dvb-core/dvbdev.c:472 dvb_register_frontend+0x61b/0x920 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+0x9aa/0xf80 drivers/media/test-drivers/vidtv/vidtv_bridge.c:510 platform_probe+0xf9/0x190 drivers/base/platform.c:1432 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x267/0xaf0 drivers/base/dd.c:709 __driver_probe_device+0x1ef/0x380 drivers/base/dd.c:871 driver_probe_device+0x4f/0x240 drivers/base/dd.c:901 __driver_attach+0x34c/0x640 drivers/base/dd.c:1295 bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383 bus_add_driver+0x345/0x670 drivers/base/bus.c:756 driver_register+0x23a/0x320 drivers/base/driver.c:249 vidtv_bridge_init+0x28/0x50 drivers/media/test-drivers/vidtv/vidtv_bridge.c:600 do_one_initcall+0x250/0x870 init/main.c:1392 do_initcall_level+0x104/0x190 init/main.c:1454 do_initcalls+0x59/0xa0 init/main.c:1470 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1703 kernel_init+0x1d/0x1d0 init/main.c:1593 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 28807: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6251 [inline] kfree+0x1c5/0x640 mm/slub.c:6566 dvb_free_device drivers/media/dvb-core/dvbdev.c:616 [inline] kref_put include/linux/kref.h:65 [inline] dvb_device_put drivers/media/dvb-core/dvbdev.c:629 [inline] dvb_generic_release+0x11d/0x1b0 drivers/media/dvb-core/dvbdev.c:169 dvb_frontend_release+0x132/0x4d0 drivers/media/dvb-core/dvb_frontend.c:2914 __fput+0x44f/0xa60 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x193/0x680 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] __do_fast_syscall_32+0x45b/0x6f0 arch/x86/entry/syscall_32.c:310 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e The buggy address belongs to the object at ffff88802cf66600 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 60 bytes inside of freed 256-byte region [ffff88802cf66600, ffff88802cf66700) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2cf66 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813fe17b40 dead000000000122 0000000000000000 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe17b40 dead000000000122 0000000000000000 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 17444043536, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853 prep_new_page mm/page_alloc.c:1861 [inline] get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab+0x77/0x660 mm/slub.c:3467 new_slab mm/slub.c:3525 [inline] refill_objects+0x339/0x3d0 mm/slub.c:7272 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652 alloc_from_pcs mm/slub.c:4750 [inline] slab_alloc_node mm/slub.c:4884 [inline] __kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5415 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] bus_add_driver+0x162/0x670 drivers/base/bus.c:740 driver_register+0x23a/0x320 drivers/base/driver.c:249 usb_register_driver+0x1e4/0x390 drivers/usb/core/driver.c:1078 do_one_initcall+0x250/0x870 init/main.c:1392 do_initcall_level+0x104/0x190 init/main.c:1454 do_initcalls+0x59/0xa0 init/main.c:1470 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1703 kernel_init+0x1d/0x1d0 init/main.c:1593 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 page_owner free stack trace missing Memory state around the buggy address: ffff88802cf66500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88802cf66580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88802cf66600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802cf66680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802cf66700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== ---------------- Code disassembly (best guess): 0: 90 nop 1: 85 d2 test %edx,%edx 3: 74 0a je 0xf 5: 89 ce mov %ecx,%esi 7: 81 e6 ff 0f 00 00 and $0xfff,%esi d: 89 32 mov %esi,(%rdx) f: 85 c0 test %eax,%eax 11: 74 05 je 0x18 13: c1 e9 0c shr $0xc,%ecx 16: 89 08 mov %ecx,(%rax) 18: 31 c0 xor %eax,%eax 1a: 5e pop %rsi 1b: 5d pop %rbp 1c: c3 ret 1d: 90 nop 1e: 0f 1f 00 nopl (%rax) 21: 51 push %rcx 22: 52 push %rdx 23: 55 push %rbp 24: 89 e5 mov %esp,%ebp 26: 0f 34 sysenter 28: cd 80 int $0x80 * 2a: 5d pop %rbp <-- trapping instruction 2b: 5a pop %rdx 2c: 59 pop %rcx 2d: c3 ret 2e: 90 nop 2f: 90 nop 30: 90 nop 31: 90 nop 32: 90 nop 33: 90 nop 34: 90 nop 35: 90 nop 36: 90 nop 37: 90 nop 38: 90 nop 39: 90 nop 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 90 nop 3e: 58 pop %rax 3f: b8 .byte 0xb8