================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline] BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: null-ptr-deref in refcount_read include/linux/refcount.h:170 [inline] BUG: KASAN: null-ptr-deref in __refcount_add_not_zero include/linux/refcount.h:176 [inline] BUG: KASAN: null-ptr-deref in __refcount_inc_not_zero include/linux/refcount.h:317 [inline] BUG: KASAN: null-ptr-deref in refcount_inc_not_zero include/linux/refcount.h:335 [inline] BUG: KASAN: null-ptr-deref in kref_get_unless_zero include/linux/kref.h:133 [inline] BUG: KASAN: null-ptr-deref in l2cap_chan_hold_unless_zero+0x98/0x264 net/bluetooth/l2cap_core.c:511 Read of size 4 at addr 0000000000000008 by task syz.0.160/5373 CPU: 0 UID: 0 PID: 5373 Comm: syz.0.160 Not tainted syzkaller #0 PREEMPT 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_report+0x58/0x84 mm/kasan/report.c:485 kasan_report+0x8c/0xc4 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x17c/0x1ac mm/kasan/generic.c:200 __kasan_check_read+0x20/0x30 mm/kasan/shadow.c:31 instrument_atomic_read include/linux/instrumented.h:82 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] refcount_read include/linux/refcount.h:170 [inline] __refcount_add_not_zero include/linux/refcount.h:176 [inline] __refcount_inc_not_zero include/linux/refcount.h:317 [inline] refcount_inc_not_zero include/linux/refcount.h:335 [inline] kref_get_unless_zero include/linux/kref.h:133 [inline] l2cap_chan_hold_unless_zero+0x98/0x264 net/bluetooth/l2cap_core.c:511 l2cap_sock_cleanup_listen+0x94/0x508 net/bluetooth/l2cap_sock.c:1535 l2cap_sock_release+0x68/0x208 net/bluetooth/l2cap_sock.c:1480 __sock_release+0xa0/0x1d4 net/socket.c:710 sock_close+0x24/0x38 net/socket.c:1501 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c 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:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __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] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 ================================================================== Unable to handle kernel paging request at virtual address dfff800000000001 KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] Mem abort info: ESR = 0x0000000096000005 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x05: level 1 translation fault Data abort info: ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [dfff800000000001] address between user and kernel address ranges Internal error: Oops: 0000000096000005 [#1] SMP Modules linked in: CPU: 0 UID: 0 PID: 5373 Comm: syz.0.160 Tainted: G B syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] pc : atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline] pc : refcount_read include/linux/refcount.h:170 [inline] pc : __refcount_add_not_zero include/linux/refcount.h:176 [inline] pc : __refcount_inc_not_zero include/linux/refcount.h:317 [inline] pc : refcount_inc_not_zero include/linux/refcount.h:335 [inline] pc : kref_get_unless_zero include/linux/kref.h:133 [inline] pc : l2cap_chan_hold_unless_zero+0x9c/0x264 net/bluetooth/l2cap_core.c:511 lr : instrument_atomic_read include/linux/instrumented.h:82 [inline] lr : atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] lr : refcount_read include/linux/refcount.h:170 [inline] lr : __refcount_add_not_zero include/linux/refcount.h:176 [inline] lr : __refcount_inc_not_zero include/linux/refcount.h:317 [inline] lr : refcount_inc_not_zero include/linux/refcount.h:335 [inline] lr : kref_get_unless_zero include/linux/kref.h:133 [inline] lr : l2cap_chan_hold_unless_zero+0x98/0x264 net/bluetooth/l2cap_core.c:511 sp : ffff800099dc7ac0 x29: ffff800099dc7b20 x28: dfff800000000000 x27: 000000000c2e0003 x26: ffff0000c1e1c690 x25: ffff0000c5370000 x24: ffff8000879d8560 x23: 0000000000000008 x22: ffff800099dc7ac0 x21: ffff7000133b8f58 x20: dfff800000000000 x19: 0000000000000000 x18: 00000000ffffffff x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d x14: 3d3d3d3d3d3d3d3d x13: 0000000000000001 x12: 0000000000000000 x11: 0000000000000000 x10: ffff700011456b21 x9 : 0000000000000000 x8 : 0000000000000001 x7 : 0000000000000000 x6 : ffff80008048ce54 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f6ad8 x2 : 0000000000000000 x1 : ffff0000dd3f0000 x0 : 0000000000000000 Call trace: raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] (P) atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline] (P) refcount_read include/linux/refcount.h:170 [inline] (P) __refcount_add_not_zero include/linux/refcount.h:176 [inline] (P) __refcount_inc_not_zero include/linux/refcount.h:317 [inline] (P) refcount_inc_not_zero include/linux/refcount.h:335 [inline] (P) kref_get_unless_zero include/linux/kref.h:133 [inline] (P) l2cap_chan_hold_unless_zero+0x9c/0x264 net/bluetooth/l2cap_core.c:511 (P) l2cap_sock_cleanup_listen+0x94/0x508 net/bluetooth/l2cap_sock.c:1535 l2cap_sock_release+0x68/0x208 net/bluetooth/l2cap_sock.c:1480 __sock_release+0xa0/0x1d4 net/socket.c:710 sock_close+0x24/0x38 net/socket.c:1501 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c 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:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __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] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 Code: 91002277 390012a8 96c04c2e d343fee8 (38f46908) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: 91002277 add x23, x19, #0x8 4: 390012a8 strb w8, [x21, #4] 8: 96c04c2e bl 0xfffffffffb0130c0 c: d343fee8 lsr x8, x23, #3 * 10: 38f46908 ldrsb w8, [x8, x20] <-- trapping instruction