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88a47f1659
When passing a equal or more then 32 bytes long string to psi_write(),
psi_write() copies 31 bytes to its buf and overwrites buf[30]
with '\0'. Which makes the input string 1 byte shorter than
it should be.
Fix it by copying sizeof(buf) bytes when nbytes >= sizeof(buf).
This does not cause problems in normal use case like:
"some 500000 10000000" or "full 500000 10000000" because they
are less than 32 bytes in length.
/* assuming nbytes == 35 */
char buf[32];
buf_size = min(nbytes, (sizeof(buf) - 1)); /* buf_size = 31 */
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
buf[buf_size - 1] = '\0'; /* buf[30] = '\0' */
Before:
%cd /proc/pressure/
%echo "123456789|123456789|123456789|1234" > memory
[ 22.473497] nbytes=35,buf_size=31
[ 22.473775] 123456789|123456789|123456789| (print 30 chars)
%sh: write error: Invalid argument
%echo "123456789|123456789|123456789|1" > memory
[ 64.916162] nbytes=32,buf_size=31
[ 64.916331] 123456789|123456789|123456789| (print 30 chars)
%sh: write error: Invalid argument
After:
%cd /proc/pressure/
%echo "123456789|123456789|123456789|1234" > memory
[ 254.837863] nbytes=35,buf_size=32
[ 254.838541] 123456789|123456789|123456789|1 (print 31 chars)
%sh: write error: Invalid argument
%echo "123456789|123456789|123456789|1" > memory
[ 9965.714935] nbytes=32,buf_size=32
[ 9965.715096] 123456789|123456789|123456789|1 (print 31 chars)
%sh: write error: Invalid argument
Also remove the superfluous parentheses.
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Cc: <linux-mediatek@lists.infradead.org>
Cc: <wsd_upstream@mediatek.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190912103452.13281-1-miles.chen@mediatek.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 4adcdcea71)
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I9371b4d5e465bb8b84ff7adf5f40f30696c6ff70
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.