linux-kernel - Re: [PATCH] io_uring: fix free of unallocated buffer list

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Date:   Thu, 21 Jul 2022 12:03:14 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Dylan Yudaken <dylany@...com>, Jens Axboe <axboe@...nel.dk>,
        io-uring@...r.kernel.org
Cc:     Kernel-team@...com, linux-kernel@...r.kernel.org,
        Dipanjan Das <mail.dipanjan.das@...il.com>
Subject: Re: [PATCH] io_uring: fix free of unallocated buffer list

On 7/21/22 12:01, Dylan Yudaken wrote:
> in the error path of io_register_pbuf_ring, only free bl if it was
> allocated.

Reviewed-by: Pavel Begunkov <asml.silence@...il.com>


> Reported-by: Dipanjan Das <mail.dipanjan.das@...il.com>
> Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers")
> Signed-off-by: Dylan Yudaken <dylany@...com>
> ---
>   fs/io_uring.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index a01ea49f3017..2b7bb62c7805 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -12931,7 +12931,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
>   {
>   	struct io_uring_buf_ring *br;
>   	struct io_uring_buf_reg reg;
> -	struct io_buffer_list *bl;
> +	struct io_buffer_list *bl, *free_bl = NULL;
>   	struct page **pages;
>   	int nr_pages;
>   
> @@ -12963,7 +12963,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
>   		if (bl->buf_nr_pages || !list_empty(&bl->buf_list))
>   			return -EEXIST;
>   	} else {
> -		bl = kzalloc(sizeof(*bl), GFP_KERNEL);
> +		free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
>   		if (!bl)
>   			return -ENOMEM;
>   	}
> @@ -12972,7 +12972,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
>   			     struct_size(br, bufs, reg.ring_entries),
>   			     &nr_pages);
>   	if (IS_ERR(pages)) {
> -		kfree(bl);
> +		kfree(free_bl);
>   		return PTR_ERR(pages);
>   	}
>   
> 
> base-commit: ff6992735ade75aae3e35d16b17da1008d753d28

-- 
Pavel Begunkov