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    Subject[PATCH 5.1 022/115] mm/list_lru.c: fix memory leak in __memcg_init_list_lru_node
    Date
    From: Shakeel Butt <shakeelb@google.com>

    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@google.com
    Fixes: 60d3fd32a7a9 ("list_lru: introduce per-memcg lists")
    Reported-by: syzbot+f90a420dfe2b1b03cb2c@syzkaller.appspotmail.com
    Signed-off-by: Shakeel Butt <shakeelb@google.com>
    Acked-by: Michal Hocko <mhocko@suse.com>
    Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
    Cc: <stable@vger.kernel.org> [4.0+]
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- a/mm/list_lru.c
    +++ b/mm/list_lru.c
    @@ -353,7 +353,7 @@ 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;
    }


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