[Bug 1525578] [NEW] buffer overflow in getmntent

[Phillip Susi]

Public bug reported:

While running valgrind on gparted I noticed a buffer overflow reported
in getmntent().  I wrote a simple reproducer and verified it is a bug in
libc.  valgrind shows that it touches 1 byte before the start of the
buffer it allocated.

Attaching the reproducer and a copy of my /etc/fstab that it is running
on when it does this.  When run on /proc/mounts, the bug does not occur.

** Affects: glibc (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "demo.c"
   https://bugs.launchpad.net/bugs/1525578/+attachment/4533843/+files/demo.c

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Title:
  buffer overflow in getmntent

Status in glibc package in Ubuntu:
  New

Bug description:
  While running valgrind on gparted I noticed a buffer overflow reported
  in getmntent().  I wrote a simple reproducer and verified it is a bug
  in libc.  valgrind shows that it touches 1 byte before the start of
  the buffer it allocated.

  Attaching the reproducer and a copy of my /etc/fstab that it is
  running on when it does this.  When run on /proc/mounts, the bug does
  not occur.

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