From 09c2e76ed734a1d36470d257a778aaba28e86531 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 8 Jan 2019 15:23:00 -0800 Subject: [PATCH] slab: alien caches must not be initialized if the allocation of the alien cache failed Callers of __alloc_alien() check for NULL. We must do the same check in __alloc_alien_cache to avoid NULL pointer dereferences on allocation failures. Link: http://lkml.kernel.org/r/010001680f42f192-82b4e12e-1565-4ee0-ae1f-1e98974906aa-000000@email.amazonses.com Fixes: 49dfc304ba241 ("slab: use the lock on alien_cache, instead of the lock on array_cache") Fixes: c8522a3a5832b ("Slab: introduce alloc_alien") Signed-off-by: Christoph Lameter Reported-by: syzbot+d6ed4ec679652b4fd4e4@syzkaller.appspotmail.com Reviewed-by: Andrew Morton Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 73fe23e649c9..78eb8c5bf4e4 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -666,8 +666,10 @@ static struct alien_cache *__alloc_alien_cache(int node, int entries, struct alien_cache *alc = NULL; alc = kmalloc_node(memsize, gfp, node); - init_arraycache(&alc->ac, entries, batch); - spin_lock_init(&alc->lock); + if (alc) { + init_arraycache(&alc->ac, entries, batch); + spin_lock_init(&alc->lock); + } return alc; } -- 2.39.5