On Sat, May 25, 2019 at 7:38 PM syzbot <syzbot+83c135be90fc92db7e13@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: c50bbf61 Merge tag 'platform-drivers-x86-v5.2-2' of git://.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=12130c9aa00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=fc045131472947d7 > dashboard link: https://syzkaller.appspot.com/bug?extid=83c135be90fc92db7e13 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12e7d84ca00000 >From the repro looks like #syz dup: KASAN: slab-out-of-bounds Read in class_equal +bpf mailing list If bpf maps started badly smashing memory in a way that KASAN can't detect, please fix asap. Or we will start getting dozens of random reports. The usual question: why does not KASAN detect the root cause smash? How can we make it detect it? > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+83c135be90fc92db7e13@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KASAN: use-after-free in class_equal+0x40/0x50 > kernel/locking/lockdep.c:1527 > Read of size 8 at addr ffff88807aedf360 by task syz-executor.0/9275 > > CPU: 0 PID: 9275 Comm: syz-executor.0 Not tainted 5.2.0-rc1+ #7 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > > Allocated by task 9264: > save_stack+0x23/0x90 mm/kasan/common.c:71 > set_track mm/kasan/common.c:79 [inline] > __kasan_kmalloc mm/kasan/common.c:489 [inline] > __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462 > kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497 > slab_post_alloc_hook mm/slab.h:437 [inline] > slab_alloc mm/slab.c:3326 [inline] > kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3488 > getname_flags fs/namei.c:138 [inline] > getname_flags+0xd6/0x5b0 fs/namei.c:128 > getname+0x1a/0x20 fs/namei.c:209 > do_sys_open+0x2c9/0x5d0 fs/open.c:1064 > __do_sys_open fs/open.c:1088 [inline] > __se_sys_open fs/open.c:1083 [inline] > __x64_sys_open+0x7e/0xc0 fs/open.c:1083 > do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Freed by task 9264: > save_stack+0x23/0x90 mm/kasan/common.c:71 > set_track mm/kasan/common.c:79 [inline] > __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451 > kasan_slab_free+0xe/0x10 mm/kasan/common.c:459 > __cache_free mm/slab.c:3432 [inline] > kmem_cache_free+0x86/0x260 mm/slab.c:3698 > putname+0xef/0x130 fs/namei.c:259 > do_sys_open+0x318/0x5d0 fs/open.c:1079 > __do_sys_open fs/open.c:1088 [inline] > __se_sys_open fs/open.c:1083 [inline] > __x64_sys_open+0x7e/0xc0 fs/open.c:1083 > do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > The buggy address belongs to the object at ffff88807aede580 > which belongs to the cache names_cache of size 4096 > The buggy address is located 3552 bytes inside of > 4096-byte region [ffff88807aede580, ffff88807aedf580) > The buggy address belongs to the page: > page:ffffea0001ebb780 refcount:1 mapcount:0 mapping:ffff8880aa596c40 > index:0x0 compound_mapcount: 0 > flags: 0x1fffc0000010200(slab|head) > raw: 01fffc0000010200 ffffea0001ebb708 ffffea0001ebb908 ffff8880aa596c40 > raw: 0000000000000000 ffff88807aede580 0000000100000001 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff88807aedf200: 00 00 fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff88807aedf280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb f1 f1 > > ffff88807aedf300: f1 f1 00 f2 f2 f2 00 f2 f2 f2 fb fb fb fb 00 00 > ^ > ffff88807aedf380: 00 f3 f3 f3 f3 f3 fb fb fb fb fb fb fb fb fb fb > ffff88807aedf400: fb fb fb fb fb fb fb fb fb fb fb fb fb 00 00 00 > ================================================================== > > > --- > This bug 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 bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/0000000000001a546b0589b9c74f%40google.com. > For more options, visit https://groups.google.com/d/optout.
