On Thu, 21 Jan 2021 at 19:30, syzbot <syzbot+70ba6cae2f44c82dc...@syzkaller.appspotmail.com> wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: 9791581c Merge tag 'for-5.11-rc4-tag' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=13cd09a4d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=39701af622f054a9 > dashboard link: https://syzkaller.appspot.com/bug?extid=70ba6cae2f44c82dcb76 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133d8030d00000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+70ba6cae2f44c82dc...@syzkaller.appspotmail.com > > ================================================================================ > UBSAN: array-index-out-of-bounds in drivers/net/hamradio/6pack.c:845:16 > index 400 is out of range for type 'unsigned char [400]' > CPU: 1 PID: 8 Comm: kworker/u4:0 Not tainted 5.11.0-rc4-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Workqueue: events_unbound flush_to_ldisc > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:356 > decode_data.part.0+0x2c8/0x2e0 drivers/net/hamradio/6pack.c:845
It looks like this might be due to a race condition; syzbot had detected a data race in this code a while back, but it seems this was never fixed: https://lore.kernel.org/lkml/000000000000bbb17d05a1954...@google.com/ > decode_data drivers/net/hamradio/6pack.c:965 [inline] > sixpack_decode drivers/net/hamradio/6pack.c:968 [inline] > sixpack_receive_buf drivers/net/hamradio/6pack.c:458 [inline] > sixpack_receive_buf+0xd8c/0x1320 drivers/net/hamradio/6pack.c:435 > tty_ldisc_receive_buf+0x14a/0x190 drivers/tty/tty_buffer.c:465 > tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:38 > receive_buf drivers/tty/tty_buffer.c:481 [inline] > flush_to_ldisc+0x20d/0x380 drivers/tty/tty_buffer.c:533 > process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 > kthread+0x3b1/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 > ================================================================================ Thanks, -- Marco