===================================================== BUG: KMSAN: uninit-value in kmsan_check_memory+0xd/0x10 mm/kmsan/kmsan_hooks.c:428 CPU: 1 PID: 18352 Comm: syz-executor.3 Not tainted 5.8.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1df/0x240 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121 kmsan_internal_check_memory+0x238/0x3d0 mm/kmsan/kmsan.c:423 kmsan_check_memory+0xd/0x10 mm/kmsan/kmsan_hooks.c:428 instrument_copy_to_user include/linux/instrumented.h:91 [inline] copyout lib/iov_iter.c:142 [inline] _copy_to_iter+0x3d4/0x26e0 lib/iov_iter.c:631 copy_to_iter include/linux/uio.h:138 [inline] memcpy_to_msg include/linux/skbuff.h:3571 [inline] bcm_recvmsg+0x25a/0x740 net/can/bcm.c:1612 ____sys_recvmsg+0xf58/0x1020 net/socket.c:886 ___sys_recvmsg net/socket.c:2617 [inline] do_recvmmsg+0x99c/0x1ee0 net/socket.c:2715 __sys_recvmmsg net/socket.c:2794 [inline] __do_sys_recvmmsg net/socket.c:2817 [inline] __se_sys_recvmmsg+0x1d1/0x350 net/socket.c:2810 __x64_sys_recvmmsg+0x62/0x80 net/socket.c:2810 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c1d9 Code: Bad RIP value. RSP: 002b:00007f01b54d0c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 0000000000024b40 RCX: 000000000045c1d9 RDX: 0000000000000002 RSI: 0000000020003e40 RDI: 0000000000000003 RBP: 000000000078bf50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000040012123 R11: 0000000000000246 R12: 000000000078bf0c R13: 0000000000c9fb6f R14: 00007f01b54d19c0 R15: 000000000078bf0c Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310 kmsan_memcpy_memmove_metadata+0x272/0x2e0 mm/kmsan/kmsan.c:247 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:267 __msan_memcpy+0x43/0x50 mm/kmsan/kmsan_instr.c:116 skb_put_data include/linux/skbuff.h:2260 [inline] bcm_send_to_user+0x250/0x820 net/can/bcm.c:327 bcm_tx_timeout_handler+0x5d0/0x620 net/can/bcm.c:413 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0xa61/0x1340 kernel/time/hrtimer.c:1584 hrtimer_run_softirq+0x1b2/0x2b0 kernel/time/hrtimer.c:1601 __do_softirq+0x311/0x83d kernel/softirq.c:293 Local variable ----msg_head@bcm_tx_timeout_handler created at: bcm_tx_timeout_handler+0x4f/0x620 net/can/bcm.c:398 bcm_tx_timeout_handler+0x4f/0x620 net/can/bcm.c:398 Bytes 12-15 of 56 are uninitialized Memory access of size 56 starts at ffff9ff10a123000 =====================================================