linux-kernel - [PATCH 1/5] mm, slub: fix two bugs in slab_debug_trace

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Message-ID: <20210916123920.48704-2-linmiaohe@huawei.com>
Date:   Thu, 16 Sep 2021 20:39:16 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <cl@...ux.com>, <penberg@...nel.org>,
        <rientjes@...gle.com>, <iamjoonsoo.kim@....com>, <vbabka@...e.cz>
CC:     <gregkh@...uxfoundation.org>, <faiyazm@...eaurora.org>,
        <andreyknvl@...il.com>, <ryabinin.a.a@...il.com>,
        <thgarnie@...gle.com>, <keescook@...omium.org>,
        <bharata@...ux.ibm.com>, <guro@...com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH 1/5] mm, slub: fix two bugs in slab_debug_trace_open()

It's possible that __seq_open_private() will return NULL. So we should
check t before using lest dereferencing NULL pointer. And in error paths,
we forgot to release private buffer via seq_release_private(). Memory
will leak in these paths.

Fixes: 64dd68497be7 ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/slub.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 3d2025f7163b..ed160b6c54f8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -6108,9 +6108,14 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
 	struct kmem_cache *s = file_inode(filep)->i_private;
 	unsigned long *obj_map;
 
+	if (!t)
+		return -ENOMEM;
+
 	obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
-	if (!obj_map)
+	if (!obj_map) {
+		seq_release_private(inode, filep);
 		return -ENOMEM;
+	}
 
 	if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0)
 		alloc = TRACK_ALLOC;
@@ -6119,6 +6124,7 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
 
 	if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) {
 		bitmap_free(obj_map);
+		seq_release_private(inode, filep);
 		return -ENOMEM;
 	}
 
-- 
2.23.0