From dde3c6b72a16c2db826f54b2d49bdea26c3534a2 Mon Sep 17 00:00:00 2001 From: Wang Hai Date: Wed, 3 Jun 2020 15:56:21 -0700 Subject: [PATCH] mm/slub: fix a memory leak in sysfs_slab_add() syzkaller reports for memory leak when kobject_init_and_add() returns an error in the function sysfs_slab_add() [1] When this happened, the function kobject_put() is not called for the corresponding kobject, which potentially leads to memory leak. This patch fixes the issue by calling kobject_put() even if kobject_init_and_add() fails. [1] BUG: memory leak unreferenced object 0xffff8880a6d4be88 (size 8): comm "syz-executor.3", pid 946, jiffies 4295772514 (age 18.396s) hex dump (first 8 bytes): 70 69 64 5f 33 00 ff ff pid_3... backtrace: kstrdup+0x35/0x70 mm/util.c:60 kstrdup_const+0x3d/0x50 mm/util.c:82 kvasprintf_const+0x112/0x170 lib/kasprintf.c:48 kobject_set_name_vargs+0x55/0x130 lib/kobject.c:289 kobject_add_varg lib/kobject.c:384 [inline] kobject_init_and_add+0xd8/0x170 lib/kobject.c:473 sysfs_slab_add+0x1d8/0x290 mm/slub.c:5811 __kmem_cache_create+0x50a/0x570 mm/slub.c:4384 create_cache+0x113/0x1e0 mm/slab_common.c:407 kmem_cache_create_usercopy+0x1a1/0x260 mm/slab_common.c:505 kmem_cache_create+0xd/0x10 mm/slab_common.c:564 create_pid_cachep kernel/pid_namespace.c:54 [inline] create_pid_namespace kernel/pid_namespace.c:96 [inline] copy_pid_ns+0x77c/0x8f0 kernel/pid_namespace.c:148 create_new_namespaces+0x26b/0xa30 kernel/nsproxy.c:95 unshare_nsproxy_namespaces+0xa7/0x1e0 kernel/nsproxy.c:229 ksys_unshare+0x3d2/0x770 kernel/fork.c:2969 __do_sys_unshare kernel/fork.c:3037 [inline] __se_sys_unshare kernel/fork.c:3035 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3035 do_syscall_64+0xa1/0x530 arch/x86/entry/common.c:295 Fixes: 80da026a8e5d ("mm/slub: fix slab double-free in case of duplicate sysfs filename") Reported-by: Hulk Robot Signed-off-by: Wang Hai Signed-off-by: Andrew Morton Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Link: http://lkml.kernel.org/r/20200602115033.1054-1-wanghai38@huawei.com Signed-off-by: Linus Torvalds --- mm/slub.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 336be3224092..527209d63278 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5835,8 +5835,10 @@ static int sysfs_slab_add(struct kmem_cache *s) s->kobj.kset = kset; err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); - if (err) + if (err) { + kobject_put(&s->kobj); goto out; + } err = sysfs_create_group(&s->kobj, &slab_attr_group); if (err)