proc: revalidate kernel thread inodes to root:root
authorAlexey Dobriyan <adobriyan@gmail.com>
Fri, 20 Apr 2018 21:56:03 +0000 (14:56 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 21 Apr 2018 00:18:35 +0000 (17:18 -0700)
commit2e0ad552f5f8cd0fda02bc45fcd2b89821c62fd1
tree1b22f2e03dc3d0e82048a454b3daeb5e54efd11b
parent1e6306652ba18723015d1b4967fe9de55f042499
proc: revalidate kernel thread inodes to root:root

task_dump_owner() has the following code:

mm = task->mm;
if (mm) {
if (get_dumpable(mm) != SUID_DUMP_USER) {
uid = ...
}
}

Check for ->mm is buggy -- kernel thread might be borrowing mm
and inode will go to some random uid:gid pair.

Link: http://lkml.kernel.org/r/20180412220109.GA20978@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/proc/base.c