Re: [PATCH v2] crypto: scompress - fix req->dst buffer overflow

[Barry Song]

On Wed, Dec 27, 2023 at 5:35 PM <chengming.zhou@xxxxxxxxx> wrote:
>
> From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
>
> The req->dst buffer size should be checked before copying from the
> scomp_scratch->dst to avoid req->dst buffer overflow problem.
>
> Fixes: 1ab53a77b772 ("crypto: acomp - add driver-side scomp interface")
> Reported-by: syzbot+3eff5e51bf1db122a16e@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://lore.kernel.org/all/0000000000000b05cd060d6b5511@xxxxxxxxxx/
> Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
> ---
> v2:
>  - change error code to ENOSPC.

Reviewed-by: Barry Song <v-songbaohua@xxxxxxxx>


> ---
>  crypto/scompress.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/crypto/scompress.c b/crypto/scompress.c
> index 442a82c9de7d..b108a30a7600 100644
> --- a/crypto/scompress.c
> +++ b/crypto/scompress.c
> @@ -117,6 +117,7 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
>         struct crypto_scomp *scomp = *tfm_ctx;
>         void **ctx = acomp_request_ctx(req);
>         struct scomp_scratch *scratch;
> +       unsigned int dlen;
>         int ret;
>
>         if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE)
> @@ -128,6 +129,8 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
>         if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
>                 req->dlen = SCOMP_SCRATCH_SIZE;
>
> +       dlen = req->dlen;
> +
>         scratch = raw_cpu_ptr(&scomp_scratch);
>         spin_lock(&scratch->lock);
>
> @@ -145,6 +148,9 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
>                                 ret = -ENOMEM;
>                                 goto out;
>                         }
> +               } else if (req->dlen > dlen) {
> +                       ret = -ENOSPC;
> +                       goto out;
>                 }
>                 scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
>                                          1);
> --
> 2.40.1
>