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>
This commit is contained in:
Chen Gang 2013-09-11 14:22:44 -07:00 committed by Linus Torvalds
parent 1ecfd533f4
commit 4c3bffc272
1 changed files with 1 additions and 1 deletions

View File

@ -652,7 +652,7 @@ int pdflush_proc_obsolete(struct ctl_table *table, int write,
{
char kbuf[] = "0\n";
if (*ppos) {
if (*ppos || *lenp < sizeof(kbuf)) {
*lenp = 0;
return 0;
}