On Thu, Sep 13, 2018 at 11:23 AM Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > On Thu, Sep 13, 2018 at 11:18 AM syzbot > <syzbot+2dcfeaf8cb49b05e8f1a@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa.. > > git tree: https://github.com/google/kmsan.git/master > > console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e > > dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a > > compiler: clang version 7.0.0 (trunk 334104) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+2dcfeaf8cb49b05e8f1a@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > random: sshd: uninitialized urandom read (32 bytes read) > > ================================================================== > > BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline] > > BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212 > > [inline] > > BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70 > > lib/iov_iter.c:716 > > CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9 > > 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+0x185/0x1d0 lib/dump_stack.c:113 > > kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125 > > kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238 > > kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261 > > copyout lib/iov_iter.c:140 [inline] > > copy_page_to_iter_iovec lib/iov_iter.c:212 [inline] > > copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716 > > generic_file_buffered_read mm/filemap.c:2185 [inline] > > generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362 > > blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930 > > call_read_iter include/linux/fs.h:1778 [inline] > > new_sync_read fs/read_write.c:406 [inline] > > __vfs_read+0x775/0x9d0 fs/read_write.c:418 > > vfs_read+0x36c/0x6b0 fs/read_write.c:452 > > ksys_read fs/read_write.c:578 [inline] > > __do_sys_read fs/read_write.c:588 [inline] > > __se_sys_read fs/read_write.c:586 [inline] > > __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586 > > do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > RIP: 0033:0x7fdeff68f310 > > RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310 > > RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003 > > RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030 > > R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8 > > > > Uninit was created at: > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline] > > kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819 > > kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889 > > __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402 > > alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093 > > alloc_pages include/linux/gfp.h:494 [inline] > > __page_cache_alloc+0x95/0x320 mm/filemap.c:946 > > pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577 > > grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089 > > block_write_begin+0xf9/0x3a0 fs/buffer.c:2068 > > blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584 > > generic_perform_write+0x438/0x9d0 mm/filemap.c:3139 > > __generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264 > > blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910 > > do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778 > > do_iter_write+0x30d/0xd50 fs/read_write.c:959 > > vfs_writev fs/read_write.c:1004 [inline] > > do_writev+0x3be/0x820 fs/read_write.c:1039 > > __do_sys_writev fs/read_write.c:1112 [inline] > > __se_sys_writev fs/read_write.c:1109 [inline] > > __x64_sys_writev+0xe1/0x120 fs/read_write.c:1109 > > do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287 > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > > Bytes 4-255 of 256 are uninitialized > > Memory access starts at ffff8801b9903000 > > ================================================================== > This particular report was caused by the repro program writing a byte > to /dev/nullb0 and /sbin/blkid reading from that device in the > background. > But it turns out that simply running `cat /dev/nullb0` already prints > uninitialized kernel memory. > Is this the intended behavior of the null block driver? A friendly ping, this bug is still reproducible on syzbot. > > --- > > 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#bug-status-tracking 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/00000000000016eb330575bd2fab%40google.com. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > Alexander Potapenko > Software Engineer > > Google Germany GmbH > Erika-Mann-Straße, 33 > 80636 München > > Geschäftsführer: Paul Manicle, Halimah DeLaine Prado > Registergericht und -nummer: Hamburg, HRB 86891 > Sitz der Gesellschaft: Hamburg -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg
