================================================================== BUG: KFENCE: use-after-free read in dvb_device_open+0xc6/0x370 drivers/media/dvb-core/dvbdev.c:99 Use-after-free read at 0xffff88823bcc2018 (in kfence-#96): dvb_device_open+0xc6/0x370 drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414 do_dentry_open+0x7e9/0x10d0 fs/open.c:882 do_open fs/namei.c:3634 [inline] path_openat+0x2635/0x2ee0 fs/namei.c:3791 do_filp_open+0x1f1/0x430 fs/namei.c:3818 do_sys_openat2+0x150/0x4b0 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] __x64_sys_openat+0x135/0x160 fs/open.c:1347 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 kfence-#96: 0xffff88823bcc2000-0xffff88823bcc20ef, size=240, cache=skbuff_head_cache allocated by task 11 on cpu 1 at 570.054507s: __alloc_skb+0xfc/0x7e0 net/core/skbuff.c:505 alloc_skb include/linux/skbuff.h:1271 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline] nsim_dev_trap_report_work+0x28f/0xaf0 drivers/net/netdevsim/dev.c:851 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 freed by task 11 on cpu 1 at 570.054541s: nsim_dev_trap_report drivers/net/netdevsim/dev.c:821 [inline] nsim_dev_trap_report_work+0x76b/0xaf0 drivers/net/netdevsim/dev.c:851 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 CPU: 1 PID: 8828 Comm: syz.2.1223 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:dvb_device_open+0xc6/0x370 drivers/media/dvb-core/dvbdev.c:99 Code: 8b 3f 4d 85 ff 0f 84 80 01 00 00 4c 89 64 24 08 4d 8d 67 18 4c 89 e5 48 c1 ed 03 80 7c 1d 00 00 74 08 4c 89 e7 e8 2a 21 0e fb <4d> 8b 2c 24 4d 85 ed 0f 84 5b 01 00 00 4c 89 e8 48 c1 e8 03 80 3c RSP: 0018:ffffc9000e9d77b0 EFLAGS: 00010246 RAX: 1ffffffff2df821b RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000008 RDI: 00000000ffffffff RBP: 1ffff11047798403 R08: ffffffff8d8ac92f R09: 1ffffffff1b15925 R10: dffffc0000000000 R11: fffffbfff1b15926 R12: ffff88823bcc2018 R13: 1ffff92001d3af04 R14: ffff888029565ff0 R15: ffff88823bcc2000 FS: 00007f50866126c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88823bcc2018 CR3: 000000007dc53000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414 do_dentry_open+0x7e9/0x10d0 fs/open.c:882 do_open fs/namei.c:3634 [inline] path_openat+0x2635/0x2ee0 fs/namei.c:3791 do_filp_open+0x1f1/0x430 fs/namei.c:3818 do_sys_openat2+0x150/0x4b0 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] __x64_sys_openat+0x135/0x160 fs/open.c:1347 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f508575c84e Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08 RSP: 002b:00007f5086611b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f50866126c0 RCX: 00007f508575c84e RDX: 0000000000040002 RSI: 00007f5086611c00 RDI: ffffffffffffff9c RBP: 00007f5086611c00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd R13: 00007f5085a16218 R14: 00007f5085a16180 R15: 00007ffe1c472ee8 ================================================================== ---------------- Code disassembly (best guess): 0: 8b 3f mov (%rdi),%edi 2: 4d 85 ff test %r15,%r15 5: 0f 84 80 01 00 00 je 0x18b b: 4c 89 64 24 08 mov %r12,0x8(%rsp) 10: 4d 8d 67 18 lea 0x18(%r15),%r12 14: 4c 89 e5 mov %r12,%rbp 17: 48 c1 ed 03 shr $0x3,%rbp 1b: 80 7c 1d 00 00 cmpb $0x0,0x0(%rbp,%rbx,1) 20: 74 08 je 0x2a 22: 4c 89 e7 mov %r12,%rdi 25: e8 2a 21 0e fb call 0xfb0e2154 * 2a: 4d 8b 2c 24 mov (%r12),%r13 <-- trapping instruction 2e: 4d 85 ed test %r13,%r13 31: 0f 84 5b 01 00 00 je 0x192 37: 4c 89 e8 mov %r13,%rax 3a: 48 c1 e8 03 shr $0x3,%rax 3e: 80 .byte 0x80 3f: 3c .byte 0x3c