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    Subject[PATCH 5.13 116/223] io_uring: fix memleak in io_init_wq_offload()
    Date
    From: Yang Yingliang <yangyingliang@huawei.com>

    [ Upstream commit 362a9e65289284f36403058eea2462d0330c1f24 ]

    I got memory leak report when doing fuzz test:

    BUG: memory leak
    unreferenced object 0xffff888107310a80 (size 96):
    comm "syz-executor.6", pid 4610, jiffies 4295140240 (age 20.135s)
    hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
    00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N..........
    backtrace:
    [<000000001974933b>] kmalloc include/linux/slab.h:591 [inline]
    [<000000001974933b>] kzalloc include/linux/slab.h:721 [inline]
    [<000000001974933b>] io_init_wq_offload fs/io_uring.c:7920 [inline]
    [<000000001974933b>] io_uring_alloc_task_context+0x466/0x640 fs/io_uring.c:7955
    [<0000000039d0800d>] __io_uring_add_tctx_node+0x256/0x360 fs/io_uring.c:9016
    [<000000008482e78c>] io_uring_add_tctx_node fs/io_uring.c:9052 [inline]
    [<000000008482e78c>] __do_sys_io_uring_enter fs/io_uring.c:9354 [inline]
    [<000000008482e78c>] __se_sys_io_uring_enter fs/io_uring.c:9301 [inline]
    [<000000008482e78c>] __x64_sys_io_uring_enter+0xabc/0xc20 fs/io_uring.c:9301
    [<00000000b875f18f>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    [<00000000b875f18f>] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80
    [<000000006b0a8484>] entry_SYSCALL_64_after_hwframe+0x44/0xae

    CPU0 CPU1
    io_uring_enter io_uring_enter
    io_uring_add_tctx_node io_uring_add_tctx_node
    __io_uring_add_tctx_node __io_uring_add_tctx_node
    io_uring_alloc_task_context io_uring_alloc_task_context
    io_init_wq_offload io_init_wq_offload
    hash = kzalloc hash = kzalloc
    ctx->hash_map = hash ctx->hash_map = hash <- one of the hash is leaked

    When calling io_uring_enter() in parallel, the 'hash_map' will be leaked,
    add uring_lock to protect 'hash_map'.

    Fixes: e941894eae31 ("io-wq: make buffered file write hashed work map per-ctx")
    Reported-by: Hulk Robot <hulkci@huawei.com>
    Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
    Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
    Link: https://lore.kernel.org/r/20210720083805.3030730-1-yangyingliang@huawei.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/io_uring.c | 6 +++++-
    1 file changed, 5 insertions(+), 1 deletion(-)

    diff --git a/fs/io_uring.c b/fs/io_uring.c
    index eeea6b8c8bee..8843f48ace27 100644
    --- a/fs/io_uring.c
    +++ b/fs/io_uring.c
    @@ -7859,15 +7859,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
    struct io_wq_data data;
    unsigned int concurrency;

    + mutex_lock(&ctx->uring_lock);
    hash = ctx->hash_map;
    if (!hash) {
    hash = kzalloc(sizeof(*hash), GFP_KERNEL);
    - if (!hash)
    + if (!hash) {
    + mutex_unlock(&ctx->uring_lock);
    return ERR_PTR(-ENOMEM);
    + }
    refcount_set(&hash->refs, 1);
    init_waitqueue_head(&hash->wait);
    ctx->hash_map = hash;
    }
    + mutex_unlock(&ctx->uring_lock);

    data.hash = hash;
    data.task = task;
    --
    2.30.2


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