mm, slub: fix two bugs in slab_debug_trace_open()

Patch series "Fixups for slub".

This series contains various bug fixes for slub.  We fix memoryleak,
use-afer-free, NULL pointer dereferencing and so on in slub.  More
details can be found in the respective changelogs.

This patch (of 5):

It's possible that __seq_open_private() will return NULL.  So we should
check it 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.

Link: https://lkml.kernel.org/r/20210916123920.48704-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20210916123920.48704-2-linmiaohe@huawei.com
Fixes: 64dd68497be7 ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Faiyaz Mohammed <faiyazm@codeaurora.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slub.c b/mm/slub.c
index 3d2025f..ed160b6 100644 (file)
--- 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;
        }