[PATCH v2] wifi: rtw89: cap firmware section_num before parsing

[Laxman Acharya Padhya <acharyalaxman8848@gmail.com>]

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].

Fixes: e3ec7017f6a2 ("rtw89: add Realtek 802.11ax driver")
Cc: stable@vger.kernel.org
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Laxman Acharya Padhya <acharyalaxman8848@gmail.com>
---
Changes in v2:
- Add the requested empty lines after the section table bounds checks.
- Add the missing Fixes tag and Ping-Ke's Acked-by tag.

 drivers/net/wireless/realtek/rtw89/fw.c | 32 +++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
index 0099c5c03e7a..b2991bc93f85 100644
--- a/drivers/net/wireless/realtek/rtw89/fw.c
+++ b/drivers/net/wireless/realtek/rtw89/fw.c
@@ -156,8 +156,24 @@ 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;
+	}
+
 	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 +471,25 @@ 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;
+	}
+
 	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