On 7/20/21 9:38 AM, Yang Yingliang wrote:
> I got memory leak report when doing fuzz test:
Reviewed-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
>
> 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@xxxxxxxxxx>
> Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> ---
> 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 0cac361bf6b8..63d3a9c2a2a6 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -7899,15 +7899,19 @@ 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;
>
--
Pavel Begunkov
