1. 16 Aug, 2021 1 commit
    • Pavel Skripkin's avatar
      block: nbd: add sanity check for first_minor · b1a81163
      Pavel Skripkin authored
      Syzbot hit WARNING in internal_create_group(). The problem was in
      too big disk->first_minor.
      
      disk->first_minor is initialized by value, which comes from userspace
      and there wasn't any sanity checks about value correctness. It can cause
      duplicate creation of sysfs files/links, because disk->first_minor will
      be passed to MKDEV() which causes truncation to byte. Since maximum
      minor value is 0xff, let's check if first_minor is correct minor number.
      
      NOTE: the root case of the reported warning was in wrong error handling
      in register_disk(), but we can avoid passing knowingly wrong values to
      sysfs API, because sysfs error messages can confuse users. For example:
      user passed 1048576 as index, but sysfs complains about duplicate
      creation of /dev/block/43:0. It's not obvious how 1048576 becomes 0.
      Log and reproducer for above example can be found on syzkaller bug
      report page.
      
      Link: https://syzkaller.appspot.com/bug?id=03c2ae9146416edf811958d5fd7acfab75b143d1
      Fixes: b0d9111a ("nbd: use an idr to keep track of nbd devices")
      Reported-by: syzbot+9937dc42271cd87d4b98@syzkaller.appspotmail.com
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarPavel Skripkin <paskripkin@gmail.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      b1a81163
  2. 14 Aug, 2021 1 commit
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  4. 10 Aug, 2021 1 commit
  5. 02 Aug, 2021 30 commits