bisecting fixing commit since 4fccc2503536a564a4ba31a1d50439854201659f building syzkaller on 2c36e7a75f8689b3da20e1a81a2ee5391f3af6e5 testing commit 4fccc2503536a564a4ba31a1d50439854201659f with gcc (GCC) 8.1.0 kernel signature: 975b589c1aed50b32a150a6b628ec0fa09e698c8b9f4f6901b970a504328f0c8 all runs: crashed: KASAN: slab-out-of-bounds Write in decode_data testing current HEAD b3a99fd385fab59d0b8b4fdfb449c1e979accab8 testing commit b3a99fd385fab59d0b8b4fdfb449c1e979accab8 with gcc (GCC) 8.1.0 kernel signature: 1951093adc04eb23a3be884e091820f000281e42a595bfddf2b918c1da77e903 run #0: crashed: KASAN: slab-out-of-bounds Write in decode_data run #1: crashed: KASAN: slab-out-of-bounds Write in decode_data run #2: crashed: KASAN: use-after-free Write in decode_data run #3: crashed: KASAN: slab-out-of-bounds Write in decode_data run #4: crashed: KASAN: slab-out-of-bounds Write in decode_data run #5: crashed: KASAN: slab-out-of-bounds Write in decode_data run #6: crashed: KASAN: slab-out-of-bounds Write in decode_data run #7: crashed: KASAN: slab-out-of-bounds Write in decode_data run #8: crashed: KASAN: slab-out-of-bounds Write in decode_data run #9: crashed: KASAN: slab-out-of-bounds Write in decode_data revisions tested: 2, total time: 24m13.581226038s (build: 16m55.756394094s, test: 6m37.396240801s) the crash still happens on HEAD commit msg: Linux 4.19.129 crash: KASAN: slab-out-of-bounds Write in decode_data IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready sp0: Synchronizing with TNC sp1: Synchronizing with TNC ================================================================== BUG: KASAN: slab-out-of-bounds in decode_data.part.2+0x23c/0x280 drivers/net/hamradio/6pack.c:863 Write of size 1 at addr ffff888091e4018e by task kworker/u4:1/23 CPU: 0 PID: 23 Comm: kworker/u4:1 Not tainted 4.19.129-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+0x123/0x177 lib/dump_stack.c:118 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:435 decode_data.part.2+0x23c/0x280 drivers/net/hamradio/6pack.c:863 decode_data drivers/net/hamradio/6pack.c:985 [inline] sixpack_decode drivers/net/hamradio/6pack.c:988 [inline] sixpack_receive_buf+0x722/0x1120 drivers/net/hamradio/6pack.c:458 tty_ldisc_receive_buf+0xff/0x1b0 drivers/tty/tty_buffer.c:460 tty_port_default_receive_buf+0x5f/0x90 drivers/tty/tty_port.c:38 receive_buf drivers/tty/tty_buffer.c:476 [inline] flush_to_ldisc+0x1aa/0x3a0 drivers/tty/tty_buffer.c:528 process_one_work+0x830/0x1670 kernel/workqueue.c:2155 worker_thread+0x85/0xb60 kernel/workqueue.c:2298 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Allocated by task 7308: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3559 getname_flags+0xb8/0x520 fs/namei.c:140 getname+0xd/0x10 fs/namei.c:211 do_sys_open+0x14c/0x350 fs/open.c:1079 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7308: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 putname+0xa8/0xe0 fs/namei.c:261 do_sys_open+0x16e/0x350 fs/open.c:1094 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888091e40a80 which belongs to the cache names_cache of size 4096 The buggy address is located 2290 bytes to the left of 4096-byte region [ffff888091e40a80, ffff888091e41a80) The buggy address belongs to the page: page:ffffea0002479000 count:1 mapcount:0 mapping:ffff88821bc47800 index:0x0 compound_mapcount: 0 flags: 0xfffe0000008100(slab|head) raw: 00fffe0000008100 ffffea0002429008 ffffea000236d588 ffff88821bc47800 raw: 0000000000000000 ffff888091e40a80 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888091e40080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888091e40100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888091e40180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888091e40200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888091e40280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== sp1: Synchronizing with TNC sp2: Synchronizing with TNC