tree 9d9583af840199d75e8e8eac61159372a74a38ba
parent 1ecfd533f4c528b0b4cc5bc115c4c47f0b5e4828
author Chen Gang <gang.chen@asianux.com> 1378934564 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1378940283 -0700

mm/backing-dev.c: check user buffer length before copying data to the related user buffer

'*lenp' may be less than "sizeof(kbuf)" so we must check this before the
next copy_to_user().

pdflush_proc_obsolete() is called by sysctl which 'procname' is
"nr_pdflush_threads", if the user passes buffer length less than
"sizeof(kbuf)", it will cause issue.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>