Subject: bug#35137: [df] incorrect parsing of /proc/self/mountinfo with \r in mount path

From: Bernhard Voelker <[email-masked]>
Date: Wed, 10 Apr 2019 09:23:59 +0200

On 4/10/19 4:15 AM, Paul Eggert wrote:
> Bernhard Voelker wrote:
> 
> +/* Find the next white space in STR, terminate the string there in place,
> +   and return that position.  Otherwise return NULL.  */
> +
> +static char *
> +terminate_at_blank (char const *str)
> +{
> +  char *s = NULL;
> +  if ((s = strchr (str, ' ')) != NULL)
> +    *s = '\0';
> +  return s;
> +}
> 
> Since the function modifies its argument, the argument type should be char *, 
> not char const *. Also, the code has an assignment in an 'if' conditional and 
> the comment is not quite right. Better is:
> 
>    /* Find the next space in STR, terminate the string there in place,
>       and return that position.  Otherwise return NULL.  */
> 
>    static char *
>    terminate_at_blank (char *str)
>    {
>      char *s = strchr (str, ' ');
>      if (s)
>        *s = '\0';
>      return s;
>    }
> 
>> +            if (! (blank = terminate_at_blank (mntroot)))
>> +              continue;
> 
> Avoid assignments in 'if' conditionals. Better is:
> 
>      blank = terminate_at_blank (target);
>      if (! blank)
>        continue;
> 
> +            if (*source == ' ')
> +              {
> +                /* The source is an empty string, which is e.g. allowed for
> +                   tmpfs: "mount -t tmpfs '' /mnt".  */
> +                *source = '\0';
> +              }
> +            else
> +              {
> +                if (! (blank = terminate_at_blank (source)))
> +                  continue;
> +              }
> 
> Since 'blank' is not used later, surely these 11 lines of code can be simplified 
> to 2 lines:
> 
>      if (! terminate_at_blank (source))
>        continue;
> 
>> +            int mntroot_s;
>> +            char *mntroot, *blank, *target, *dash, *fstype, *source;
> 
> I suggest using C99-style declaration-after-statement style rather than this 
> old-fashioned C89-style declarations-at-start-of-block style, just for the 
> changed part of the code anyway.

Thanks for the review.
Pushed with all these changes at:
https://git.sv.gnu.org/cgit/gnulib.git/commit/?id=eb8278fefa

For coreutils, I'll push the (attached) gnulib update with a NEWS entry soon,
and then work on tests.

Have a nice day,
Berny

>From b938a1badf672f8168daf71fd751e947877c9fc7 Mon Sep 17 00:00:00 2001
From: Bernhard Voelker <[email-masked]>
Date: Wed, 10 Apr 2019 09:13:27 +0200
Subject: [PATCH] gnulib: update to the latest

* gnulib: Update to latest, mainly for:
  > mountlist: make parsing /proc/self/mountinfo more robust
* NEWS: Mention the fix.

Fixes https://bugs.gnu.org/33468
---
 NEWS   | 7 +++++++
 gnulib | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 6844228be..132f2a0f3 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,13 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Bug fixes
 
+  df now correctly parses the /proc/self/mountinfo file for unusual entries
+  with '\r' in a field value ("mount -t tmpfs tmpfs /foo$'\r'bar"),
+  when the source field is empty ('mount -t tmpfs "" /mnt'), and when the
+  filesystem type contains characters like blank which need escaping.
+  [bugs introduced in coreutils-8.24 with the introduction of reading
+   the /proc/self/mountinfo file]
+
   factor again outputs immediately when stdout is a tty but stdin is not.
   [bug introduced in coreutils-8.24]
 
diff --git a/gnulib b/gnulib
index 188d87b05..eb8278fef 160000
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 188d87b05190690d6f8b0577ec65ef221a711d08
+Subproject commit eb8278fefa0bbf2a53b706bffb2c99ccfe5d7bd4
-- 
2.21.0