Hello, syzbot found the following issue on: HEAD commit: 14525656 compiler.h: reinstate missing KMSAN_INIT git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=15996087100000 kernel config: https://syzkaller.appspot.com/x/.config?x=c534a9fad6323722 dashboard link: https://syzkaller.appspot.com/bug?extid=81908a97abeec4f4f02d compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1018fc7f100000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=100846d7100000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+81908a97abeec4f4f02d@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== BUG: KMSAN: uninit-value in kmsan_check_memory+0xd/0x10 mm/kmsan/kmsan_hooks.c:428 CPU: 0 PID: 8682 Comm: syz-executor281 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 sock_recvmsg_nosec net/socket.c:886 [inline] sock_recvmsg net/socket.c:904 [inline] __sys_recvfrom+0xacd/0xae0 net/socket.c:2052 __do_sys_recvfrom net/socket.c:2070 [inline] __se_sys_recvfrom+0x111/0x130 net/socket.c:2066 __x64_sys_recvfrom+0x6e/0x90 net/socket.c:2066 do_syscall_64+0xb0/0x150 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x448cd9 Code: Bad RIP value. RSP: 002b:00007f5fbb95fd88 EFLAGS: 00000246 ORIG_RAX: 000000000000002d RAX: ffffffffffffffda RBX: 00000000006dec68 RCX: 0000000000448cd9 RDX: 0000000000000032 RSI: 0000000020000040 RDI: 0000000000000003 RBP: 00000000006dec60 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dec6c R13: ffffff7f00000001 R14: 0000000000000000 R15: 000000306e616376 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 50 are uninitialized Memory access of size 50 starts at ffff88b629809600 ===================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
