RE: [PATCH] wifi: rtw89: cap firmware section_num before parsing

[Ping-Ke Shih]

Laxman Acharya Padhya <acharyalaxman8848@xxxxxxxxx> wrote:
> rtw89_fw_bin_info.section_info has FWDL_SECTION_MAX_NUM (10) entries.
> The v0/v1 header parsers take section_num from an 8-bit firmware field
> (0..255) and write info->section_info[i] with no cap.
> rtw89_fw_download_suit() keeps that object on the stack, so a crafted
> firmware blob overflows the stack.
> 
> Reject a truncated header and a section table that does not fit in the
> firmware image before reading fw_hdr->sections[i].
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Laxman Acharya Padhya <acharyalaxman8848@xxxxxxxxx>

Acked-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx>

Logic is good to me, but please add empty lines. 

> ---
>  drivers/net/wireless/realtek/rtw89/fw.c | 30 +++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
> index 0099c5c03e7a6..57d4252ee78f0 100644
> --- a/drivers/net/wireless/realtek/rtw89/fw.c
> +++ b/drivers/net/wireless/realtek/rtw89/fw.c
> @@ -156,8 +156,23 @@ static int rtw89_fw_hdr_parser_v0(struct rtw89_dev *rtwdev, const u8 *fw, u32 le
>         if (!info)
>                 return -EINVAL;
> 
> +       if (len < sizeof(*fw_hdr)) {
> +               rtw89_err(rtwdev, "[ERR]fw header truncated\n");
> +               return -EINVAL;
> +       }
> +
>         info->section_num = le32_get_bits(fw_hdr->w6, FW_HDR_W6_SEC_NUM);
> +       if (!info->section_num || info->section_num > FWDL_SECTION_MAX_NUM) {
> +               rtw89_err(rtwdev, "[ERR]invalid fw section num %u\n",
> +                         info->section_num);
> +               return -EINVAL;
> +       }
> +
>         base_hdr_len = struct_size(fw_hdr, sections, info->section_num);
> +       if (base_hdr_len > len) {
> +               rtw89_err(rtwdev, "[ERR]fw header truncated\n");
> +               return -EINVAL;
> +       }

an empty line

>         info->dynamic_hdr_en = le32_get_bits(fw_hdr->w7, FW_HDR_W7_DYN_HDR);
>         info->idmem_share_mode = le32_get_bits(fw_hdr->w7, FW_HDR_W7_IDMEM_SHARE_MODE);
> 
> @@ -455,9 +470,24 @@ static int rtw89_fw_hdr_parser_v1(struct rtw89_dev *rtwdev, const u8 *fw, u32 le
>         int ret;
>         u32 i;
> 
> +       if (len < sizeof(*fw_hdr)) {
> +               rtw89_err(rtwdev, "[ERR]fw header truncated\n");
> +               return -EINVAL;
> +       }
> +
>         info->section_num = le32_get_bits(fw_hdr->w6, FW_HDR_V1_W6_SEC_NUM);
> +       if (!info->section_num || info->section_num > FWDL_SECTION_MAX_NUM) {
> +               rtw89_err(rtwdev, "[ERR]invalid fw section num %u\n",
> +                         info->section_num);
> +               return -EINVAL;
> +       }
> +
>         info->dsp_checksum = le32_get_bits(fw_hdr->w6, FW_HDR_V1_W6_DSP_CHKSUM);
>         base_hdr_len = struct_size(fw_hdr, sections, info->section_num);
> +       if (base_hdr_len > len) {
> +               rtw89_err(rtwdev, "[ERR]fw header truncated\n");
> +               return -EINVAL;
> +       }

an empty line

>         info->dynamic_hdr_en = le32_get_bits(fw_hdr->w7, FW_HDR_V1_W7_DYN_HDR);
>         info->idmem_share_mode = le32_get_bits(fw_hdr->w7, FW_HDR_V1_W7_IDMEM_SHARE_MODE);
> 
> --
> 2.51.2