[PATCH 4.14 21/42] slab: fix a crash by reading /proc/slab_allocators

From: Greg Kroah-Hartman
Date: Thu May 09 2019 - 14:47:00 EST

[ Upstream commit fcf88917dd435c6a4cb2830cb086ee58605a1d85 ]

The commit 510ded33e075 ("slab: implement slab_root_caches list")
changes the name of the list node within "struct kmem_cache" from "list"
to "root_caches_node", but leaks_show() still use the "list" which
causes a crash when reading /proc/slab_allocators.

You need to have CONFIG_SLAB=y and CONFIG_MEMCG=y to see the problem,
because without MEMCG all slab caches are root caches, and the "list"
node happens to be the right one.

Fixes: 510ded33e075 ("slab: implement slab_root_caches list")
Signed-off-by: Qian Cai <cai@xxxxxx>
Reviewed-by: Tobin C. Harding <tobin@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
mm/slab.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index f4658468b23e1..843ecea9e336b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4299,7 +4299,8 @@ static void show_symbol(struct seq_file *m, unsigned long address)

static int leaks_show(struct seq_file *m, void *p)
- struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
+ struct kmem_cache *cachep = list_entry(p, struct kmem_cache,
+ root_caches_node);
struct page *page;
struct kmem_cache_node *n;
const char *name;