[PATCH 4.14 09/53] mm/list_lru.c: fix memory leak in __memcg_init_list_lru_node

From: Greg Kroah-Hartman
Date: Mon Jun 17 2019 - 17:36:27 EST


From: Shakeel Butt <shakeelb@xxxxxxxxxx>

commit 3510955b327176fd4cbab5baa75b449f077722a2 upstream.

Syzbot reported following memory leak:

ffffffffda RBX: 0000000000000003 RCX: 0000000000441f79
BUG: memory leak
unreferenced object 0xffff888114f26040 (size 32):
comm "syz-executor626", pid 7056, jiffies 4294948701 (age 39.410s)
hex dump (first 32 bytes):
40 60 f2 14 81 88 ff ff 40 60 f2 14 81 88 ff ff @`......@`......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
slab_post_alloc_hook mm/slab.h:439 [inline]
slab_alloc mm/slab.c:3326 [inline]
kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
kmalloc include/linux/slab.h:547 [inline]
__memcg_init_list_lru_node+0x58/0xf0 mm/list_lru.c:352
memcg_init_list_lru_node mm/list_lru.c:375 [inline]
memcg_init_list_lru mm/list_lru.c:459 [inline]
__list_lru_init+0x193/0x2a0 mm/list_lru.c:626
alloc_super+0x2e0/0x310 fs/super.c:269
sget_userns+0x94/0x2a0 fs/super.c:609
sget+0x8d/0xb0 fs/super.c:660
mount_nodev+0x31/0xb0 fs/super.c:1387
fuse_mount+0x2d/0x40 fs/fuse/inode.c:1236
legacy_get_tree+0x27/0x80 fs/fs_context.c:661
vfs_get_tree+0x2e/0x120 fs/super.c:1476
do_new_mount fs/namespace.c:2790 [inline]
do_mount+0x932/0xc50 fs/namespace.c:3110
ksys_mount+0xab/0x120 fs/namespace.c:3319
__do_sys_mount fs/namespace.c:3333 [inline]
__se_sys_mount fs/namespace.c:3330 [inline]
__x64_sys_mount+0x26/0x30 fs/namespace.c:3330
do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xa9

This is a simple off by one bug on the error path.

Link: http://lkml.kernel.org/r/20190528043202.99980-1-shakeelb@xxxxxxxxxx
Fixes: 60d3fd32a7a9 ("list_lru: introduce per-memcg lists")
Reported-by: syzbot+f90a420dfe2b1b03cb2c@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.0+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
mm/list_lru.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -313,7 +313,7 @@ static int __memcg_init_list_lru_node(st
}
return 0;
fail:
- __memcg_destroy_list_lru_node(memcg_lrus, begin, i - 1);
+ __memcg_destroy_list_lru_node(memcg_lrus, begin, i);
return -ENOMEM;
}