kernel/kcov: unproxify debugfs file's fops
authorNicolai Stange <nicstange@gmail.com>
Tue, 24 May 2016 12:05:05 +0000 (14:05 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 15 Jun 2016 11:56:35 +0000 (04:56 -0700)
commitdf4565f9ebdc4d6dc50edc6e8fed08004e328332
tree2acc27591fed42dbe35eb1793bc4e2101b9f3d91
parent5edb56491d4812c42175980759da53388e5d86f5
kernel/kcov: unproxify debugfs file's fops

Since commit 49d200deaa68 ("debugfs: prevent access to removed files'
private data"), a debugfs file's file_operations methods get proxied
through lifetime aware wrappers.

However, only a certain subset of the file_operations members is supported
by debugfs and ->mmap isn't among them -- it appears to be NULL from the
VFS layer's perspective.

This behaviour breaks the /sys/kernel/debug/kcov file introduced
concurrently with commit 5c9a8750a640 ("kernel: add kcov code coverage").

Since that file never gets removed, there is no file removal race and thus,
a lifetime checking proxy isn't needed.

Avoid the proxying for /sys/kernel/debug/kcov by creating it via
debugfs_create_file_unsafe() rather than debugfs_create_file().

Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data")
Fixes: 5c9a8750a640 ("kernel: add kcov code coverage")
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/kcov.c