brcmfmac: backport length check in brcmf_cfg80211_escan_handler()

Fixes CVE-2017-0786

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/package/kernel/mac80211/patches/326-brcmfmac-add-length-check-in-brcmf_cfg80211_escan_ha.patch b/package/kernel/mac80211/patches/326-brcmfmac-add-length-check-in-brcmf_cfg80211_escan_ha.patch
new file mode 100644 (file)
index 0000000..63c867a
--- /dev/null
+++ b/package/kernel/mac80211/patches/326-brcmfmac-add-length-check-in-brcmf_cfg80211_escan_ha.patch
@@ -0,0 +1,63 @@
+From: Arend Van Spriel <arend.vanspriel@broadcom.com>
+Date: Tue, 12 Sep 2017 10:47:53 +0200
+Subject: [PATCH] brcmfmac: add length check in brcmf_cfg80211_escan_handler()
+
+Upon handling the firmware notification for scans the length was
+checked properly and may result in corrupting kernel heap memory
+due to buffer overruns. This fix addresses CVE-2017-0786.
+
+Cc: stable@vger.kernel.org # v4.0.x
+Cc: Kevin Cernekee <cernekee@chromium.org>
+Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
+Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
+Reviewed-by: Franky Lin <franky.lin@broadcom.com>
+Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
+Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
+---
+
+--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
++++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
+@@ -3088,6 +3088,7 @@ brcmf_cfg80211_escan_handler(struct brcm
+       struct brcmf_cfg80211_info *cfg = ifp->drvr->config;
+       s32 status;
+       struct brcmf_escan_result_le *escan_result_le;
++      u32 escan_buflen;
+       struct brcmf_bss_info_le *bss_info_le;
+       struct brcmf_bss_info_le *bss = NULL;
+       u32 bi_length;
+@@ -3104,11 +3105,23 @@ brcmf_cfg80211_escan_handler(struct brcm
+ 
+       if (status == BRCMF_E_STATUS_PARTIAL) {
+               brcmf_dbg(SCAN, "ESCAN Partial result\n");
++              if (e->datalen < sizeof(*escan_result_le)) {
++                      brcmf_err("invalid event data length\n");
++                      goto exit;
++              }
+               escan_result_le = (struct brcmf_escan_result_le *) data;
+               if (!escan_result_le) {
+                       brcmf_err("Invalid escan result (NULL pointer)\n");
+                       goto exit;
+               }
++              escan_buflen = le32_to_cpu(escan_result_le->buflen);
++              if (escan_buflen > BRCMF_ESCAN_BUF_SIZE ||
++                  escan_buflen > e->datalen ||
++                  escan_buflen < sizeof(*escan_result_le)) {
++                      brcmf_err("Invalid escan buffer length: %d\n",
++                                escan_buflen);
++                      goto exit;
++              }
+               if (le16_to_cpu(escan_result_le->bss_count) != 1) {
+                       brcmf_err("Invalid bss_count %d: ignoring\n",
+                                 escan_result_le->bss_count);
+@@ -3125,9 +3138,8 @@ brcmf_cfg80211_escan_handler(struct brcm
+               }
+ 
+               bi_length = le32_to_cpu(bss_info_le->length);
+-              if (bi_length != (le32_to_cpu(escan_result_le->buflen) -
+-                                      WL_ESCAN_RESULTS_FIXED_SIZE)) {
+-                      brcmf_err("Invalid bss_info length %d: ignoring\n",
++              if (bi_length != escan_buflen - WL_ESCAN_RESULTS_FIXED_SIZE) {
++                      brcmf_err("Ignoring invalid bss_info length: %d\n",
+                                 bi_length);
+                       goto exit;
+               }