Lin Feng acf0e7b15f sysctl.c: fix underflow value setting risk in vm_table
[ Upstream commit 3b3376f222e3ab58367d9dd405cafd09d5e37b7c ]

Apart from subsystem specific .proc_handler handler, all ctl_tables with
extra1 and extra2 members set should use proc_dointvec_minmax instead of
proc_dointvec, or the limit set in extra* never work and potentially echo
underflow values(negative numbers) is likely make system unstable.

Especially vfs_cache_pressure and zone_reclaim_mode, -1 is apparently not
a valid value, but we can set to them.  And then kernel may crash.

# echo -1 > /proc/sys/vm/vfs_cache_pressure

Link: https://lkml.kernel.org/r/20201223105535.2875-1-linf@wangsu.com
Signed-off-by: Lin Feng <linf@wangsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-17 17:03:45 +01:00
2019-09-22 10:34:46 -07:00
2019-11-10 13:41:59 -08:00
2021-03-17 17:03:44 +01:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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