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Commit f57b3087 authored by Fenghua Yu's avatar Fenghua Yu Committed by Thomas Gleixner
Browse files

x86/intel_rdt: Protect info directory from removal 



The info directory and the per-resource subdirectories of the info
directory have no reference to a struct rdtgroup in kn->priv. An attempt to
remove one of those directories results in a NULL pointer dereference.

Protect the directories from removal and return -EPERM instead of -ENOENT.

[ tglx: Massaged changelog ]

Signed-off-by: default avatarFenghua Yu <fenghua.yu@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com>
Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com>
Cc: "Ingo Molnar" <mingo@elte.hu>
Cc: "H. Peter Anvin" <h.peter.anvin@intel.com>
Link: http://lkml.kernel.org/r/1478912558-55514-1-git-send-email-fenghua.yu@intel.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 458b0d6e

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

+20 −4
Original line number Diff line number Diff line
@@ -644,16 +644,29 @@ static int parse_rdtgroupfs_options(char *data) 
 */

static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)

{

	if (kernfs_type(kn) == KERNFS_DIR)

		return kn->priv;

	if (kernfs_type(kn) == KERNFS_DIR) {

		/*

		 * All the resource directories use "kn->priv"

		 * to point to the "struct rdtgroup" for the

		 * resource. "info" and its subdirectories don't

		 * have rdtgroup structures, so return NULL here.

		 */

		if (kn == kn_info || kn->parent == kn_info)

			return NULL;

		else

			return kn->priv;

	} else {

		return kn->parent->priv;

	}

}



struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)

{

	struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);



	if (!rdtgrp)

		return NULL;



	atomic_inc(&rdtgrp->waitcount);

	kernfs_break_active_protection(kn);
@@ -670,6 +683,9 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn) 
{

	struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);



	if (!rdtgrp)

		return;



	mutex_unlock(&rdtgroup_mutex);



	if (atomic_dec_and_test(&rdtgrp->waitcount) &&
@@ -918,7 +934,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn) 
	rdtgrp = rdtgroup_kn_lock_live(kn);

	if (!rdtgrp) {

		rdtgroup_kn_unlock(kn);

		return -ENOENT;

		return -EPERM;

	}



	/* Give any tasks back to the default group */