[lxc-devel] [lxc/lxc] 8737e2: lseek - integer overflow

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/lxc/lxc
  Commit: 8737e2a8a56f2dc4c8f35ccc413d59b5c78c3a30
      https://github.com/lxc/lxc/commit/8737e2a8a56f2dc4c8f35ccc413d59b5c78c3a30
  Author: Lukasz Jagiello <lukasz at wikia-inc.com>
  Date:   2018-08-18 (Sat, 18 Aug 2018)

  Changed paths:
    M src/lxc/storage/loop.c

  Log Message:
  -----------
  lseek - integer overflow

The issue was introduced in PR (https://github.com/lxc/lxc/pull/1705):

Previous code:
```
  if (lseek(fd, size, SEEK_SET) < 0) {
    SYSERROR("Error seeking to set new loop file size");
    close(fd);
    return -1;
  }
```
New code:
```
  int fd, ret;

  [...]

  ret = lseek(fd, size, SEEK_SET);
  if (ret < 0) {
    SYSERROR("Failed to seek to set new loop file size for loop "
       "file \"%s\"", path);
    close(fd);
    return -1;
  }
```

Based on http://man7.org/linux/man-pages/man2/lseek.2.html:
> Upon successful completion, lseek() returns the resulting offset
> location as measured in bytes from the beginning of the file.

So in this case value of `size` and `size` is `uint64_t`.

This fix change declaration of `ret`, but it can be fixed in other ways.
Let me know what works for you.

This PR fix issues (https://github.com/lxc/lxc/issues/1872).

Signed-off-by: Lukasz Jagiello <lukasz at wikia-inc.com>


  Commit: 0a4f0d02d83c26f1ac8b637b7ca11546ab8b2dda
      https://github.com/lxc/lxc/commit/0a4f0d02d83c26f1ac8b637b7ca11546ab8b2dda
  Author: Christian Brauner <christian at brauner.io>
  Date:   2018-08-18 (Sat, 18 Aug 2018)

  Changed paths:
    M src/lxc/storage/loop.c

  Log Message:
  -----------
  Merge pull request #2545 from ljagiello/integer-overflow

storage/loop.c: integer overflow


Compare: https://github.com/lxc/lxc/compare/2957be64da84...0a4f0d02d83c
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