Commit f4c6b558 authored by Muchun Song's avatar Muchun Song Committed by Kaixiong Yu
Browse files

mm: kfence: fix using kfence_metadata without initialization in show_object() 

mainline inclusion
from mainline-v6.3-rc4
commit 1c86a188
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IBGU7R

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1c86a188e03156223a3409ce290b49bd4dd0403

--------------------------------

The variable kfence_metadata is initialized in kfence_init_pool(), then,
it is not initialized if kfence is disabled after booting.  In this case,
kfence_metadata will be used (e.g.  ->lock and ->state fields) without
initialization when reading /sys/kernel/debug/kfence/objects.  There will
be a warning if you enable CONFIG_DEBUG_SPINLOCK.  Fix it by creating
debugfs files when necessary.

Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com


Fixes: 0ce20dd8 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Tested-by: default avatarMarco Elver <elver@google.com>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Conflicts:
        mm/kfence/core.c
[Because OLK-5.10 didn't merge mainline commit 6b1964e6
("mm: kfence: convert to DEFINE_SEQ_ATTRIBUTE")]
Signed-off-by: default avatarKaixiong Yu <yukaixiong@huawei.com>
parent e9b08012

mm/kfence/core.c

+8 −2
Original line number Diff line number Diff line
@@ -921,10 +921,14 @@ static const struct file_operations objects_fops = { 
	.release = seq_release,

};



static int __init kfence_debugfs_init(void)

static int kfence_debugfs_init(void)

{

	struct dentry *kfence_dir = debugfs_create_dir("kfence", NULL);

	struct dentry *kfence_dir;



	if (!READ_ONCE(kfence_enabled))

		return 0;



	kfence_dir = debugfs_create_dir("kfence", NULL);

	debugfs_create_file("stats", 0444, kfence_dir, NULL, &stats_fops);



	/* Variable kfence_metadata may fail to allocate. */
@@ -1128,6 +1132,8 @@ static int kfence_init_late(void) 
	}



	kfence_init_enable();

	kfence_debugfs_init();



	return 0;

}