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From: Christian Brauner <>
Cc:,,,,, Christian Brauner <>
Subject: [PATCH 0/2] sysctl: cap file-max value at ULONG_MAX
Date: Sun, 14 Oct 2018 15:25:08 +0200	[thread overview]
Message-ID: <> (raw)


Currently, when writing

echo 18446744073709551616 > /proc/sys/fs/file-max

/proc/sys/fs/file-max will overflow and be set to 0. That quickly
crashes the system. Let's detect the overflow and set to ULONG_MAX in
this case effectively capping the value.

The patch tries to ensure that there is no other user visible change in
behavior for other values. Only when a maximum value is set for a
specific sysctl will it be capped on overflow. The details are outlined
in the commit message of the first commit.

(This patchset is in reference to


Christian Brauner (2):
  sysctl: add overflow detection to proc_get_long()
  sysctl: handle overflow for file-max

 kernel/sysctl.c | 54 ++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 12 deletions(-)


             reply	other threads:[~2018-10-14 13:25 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-14 13:25 Christian Brauner [this message]
2018-10-14 13:25 ` [PATCH 1/2] sysctl: add overflow detection to proc_get_long() Christian Brauner
2018-10-14 17:18   ` Al Viro
2018-10-14 18:53     ` Christian Brauner
2018-10-15  0:03       ` Al Viro
2018-10-15  4:47         ` Christian Brauner
2018-10-14 13:25 ` [PATCH 2/2] sysctl: handle overflow for file-max Christian Brauner

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