================================================================== BUG: KASAN: slab-out-of-bounds in decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843 Write of size 1 at addr ffff88809795504e by task kworker/u4:2/32 CPU: 0 PID: 32 Comm: kworker/u4:2 Not tainted 5.5.0-rc2-next-20191218-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:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:639 __asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:137 decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843 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+0xde4/0x1420 drivers/net/hamradio/6pack.c:435 tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:465 tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38 receive_buf drivers/tty/tty_buffer.c:481 [inline] flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:533 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 worker_thread+0x98/0xe40 kernel/workqueue.c:2410 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 9204: save_stack+0x23/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc mm/kasan/common.c:513 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 __do_kmalloc_node mm/slab.c:3616 [inline] __kmalloc_node+0x4e/0x70 mm/slab.c:3623 kmalloc_node include/linux/slab.h:579 [inline] kvmalloc_node+0x68/0x100 mm/util.c:574 kvmalloc include/linux/mm.h:650 [inline] kvzalloc include/linux/mm.h:658 [inline] alloc_netdev_mqs+0x98/0xde0 net/core/dev.c:9748 sixpack_open+0x104/0xaaf drivers/net/hamradio/6pack.c:563 tty_ldisc_open.isra.0+0xa3/0x110 drivers/tty/tty_ldisc.c:464 tty_set_ldisc+0x30e/0x6b0 drivers/tty/tty_ldisc.c:591 tiocsetd drivers/tty/tty_io.c:2337 [inline] tty_ioctl+0xe8d/0x14f0 drivers/tty/tty_io.c:2597 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 0: (stack is not available) The buggy address belongs to the object at ffff888097954000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 78 bytes to the right of 4096-byte region [ffff888097954000, ffff888097955000) The buggy address belongs to the page: page:ffffea00025e5500 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0 raw: 00fffe0000010200 ffffea00023e8608 ffffea0002807a88 ffff8880aa402000 raw: 0000000000000000 ffff888097954000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888097954f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888097954f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888097955000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888097955080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888097955100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================