queue-5.0/slab-fix-a-crash-by-reading-proc-slab_allocators.patch

   1 From 26dbb49dd6414012e56311cf7d5d0e9fa37d3d75 Mon Sep 17 00:00:00 2001
   2 From: Qian Cai <cai@lca.pw>
   3 Date: Sat, 6 Apr 2019 18:59:01 -0400
   4 Subject: slab: fix a crash by reading /proc/slab_allocators
   5
   6 [ Upstream commit fcf88917dd435c6a4cb2830cb086ee58605a1d85 ]
   7
   8 The commit 510ded33e075 ("slab: implement slab_root_caches list")
   9 changes the name of the list node within "struct kmem_cache" from "list"
  10 to "root_caches_node", but leaks_show() still use the "list" which
  11 causes a crash when reading /proc/slab_allocators.
  12
  13 You need to have CONFIG_SLAB=y and CONFIG_MEMCG=y to see the problem,
  14 because without MEMCG all slab caches are root caches, and the "list"
  15 node happens to be the right one.
  16
  17 Fixes: 510ded33e075 ("slab: implement slab_root_caches list")
  18 Signed-off-by: Qian Cai <cai@lca.pw>
  19 Reviewed-by: Tobin C. Harding <tobin@kernel.org>
  20 Cc: Tejun Heo <tj@kernel.org>
  21 Cc: Andrew Morton <akpm@linux-foundation.org>
  22 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  23 Signed-off-by: Sasha Levin <sashal@kernel.org>
  24 ---
  25  mm/slab.c | 3 ++-
  26  1 file changed, 2 insertions(+), 1 deletion(-)
  27
  28 diff --git a/mm/slab.c b/mm/slab.c
  29 index 2f2aa8eaf7d98..188c4b65255dc 100644
  30 --- a/mm/slab.c
  31 +++ b/mm/slab.c
  32 @@ -4297,7 +4297,8 @@ static void show_symbol(struct seq_file *m, unsigned long address)
  33
  34  static int leaks_show(struct seq_file *m, void *p)
  35  {
  36 -       struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
  37 +       struct kmem_cache *cachep = list_entry(p, struct kmem_cache,
  38 +                                              root_caches_node);
  39         struct page *page;
  40         struct kmem_cache_node *n;
  41         const char *name;
  42 --
  43 2.20.1
  44