Linux 4.19.42

[thirdparty/kernel/stable-queue.git] / releases / 4.19.42 / slab-fix-a-crash-by-reading-proc-slab_allocators.patch

From 34ec98605c366701b19aed8fbc5de84b880bd4bf Mon Sep 17 00:00:00 2001
From: Qian Cai <cai@lca.pw>
Date: Sat, 6 Apr 2019 18:59:01 -0400
Subject: slab: fix a crash by reading /proc/slab_allocators

[ 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@lca.pw>
Reviewed-by: Tobin C. Harding <tobin@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/slab.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index b8e0ec74330f3..018d32496e8d1 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4305,7 +4305,8 @@ 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;
-- 
2.20.1