From: Stephen Wilson <wilsons@start.ca>
Date: Sun, 13 Mar 2011 19:49:23 +0000 (-0400)
Subject: proc: make check_mem_permission() return an mm_struct on success
X-Git-Tag: v2.6.39-rc1~99^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b0db9db19858b08c46a84540acfd35f6e6487b8;p=pandora-kernel.git

proc: make check_mem_permission() return an mm_struct on success

This change allows us to take advantage of access_remote_vm(), which in turn
eliminates a security issue with the mem_write() implementation.

The previous implementation of mem_write() was insecure since the target task
could exec a setuid-root binary between the permission check and the actual
write.  Holding a reference to the target mm_struct eliminates this
vulnerability.

Signed-off-by: Stephen Wilson <wilsons@start.ca>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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