t ac40532ef0b8649e6f7f83859ea0de1c4ed08a19
author Al Viro <viro@ZenIV.linux.org.uk> 1199282997 +0000
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1199308407 -0800

restrict reading from /proc/<pid>/maps to those who share ->mm or can ptrace pid

Contents of /proc/*/maps is sensitive and may become sensitive after
open() (e.g.  if target originally shares our ->mm and later does exec
on suid-root binary).

Check at read() (actually, ->start() of iterator) time that mm_struct
we'd grabbed and locked is
 - still the ->mm of target
 - equal to reader's ->mm or the target is ptracable by reader.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
·g