orinoco: validate firmware header

Check the Agere firmware headers for validity before attempting to
download it.

Signed-off-by: David Kilroy <kilroyd@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/net/wireless/orinoco/fw.c b/drivers/net/wireless/orinoco/fw.c
index 7d2292d6ce09..9f163feb9362 100644
--- a/drivers/net/wireless/orinoco/fw.c
+++ b/drivers/net/wireless/orinoco/fw.c
@@ -43,6 +43,33 @@ struct orinoco_fw_header {
         char signature[0];      /* FW signature length headersize-20 */
 } __attribute__ ((packed));
 
+/* Check the range of various header entries. Return a pointer to a
+ * description of the problem, or NULL if everything checks out. */
+static const char *validate_fw(const struct orinoco_fw_header *hdr, size_t len)
+{
+        u16 hdrsize;
+
+        if (len < sizeof(*hdr))
+                return "image too small";
+        if (memcmp(hdr->hdr_vers, "HFW", 3) != 0)
+                return "format not recognised";
+
+        hdrsize = le16_to_cpu(hdr->headersize);
+        if (hdrsize > len)
+                return "bad headersize";
+        if ((hdrsize + le32_to_cpu(hdr->block_offset)) > len)
+                return "bad block offset";
+        if ((hdrsize + le32_to_cpu(hdr->pdr_offset)) > len)
+                return "bad PDR offset";
+        if ((hdrsize + le32_to_cpu(hdr->pri_offset)) > len)
+                return "bad PRI offset";
+        if ((hdrsize + le32_to_cpu(hdr->compat_offset)) > len)
+                return "bad compat offset";
+
+        /* TODO: consider adding a checksum or CRC to the firmware format */
+        return NULL;
+}
+
 /* Download either STA or AP firmware into the card. */
 static int
 orinoco_dl_firmware(struct orinoco_private *priv,
@@ -58,6 +85,7 @@ orinoco_dl_firmware(struct orinoco_private *priv,
         const unsigned char *first_block;
         const unsigned char *end;
         const char *firmware;
+        const char *fw_err;
         struct net_device *dev = priv->ndev;
         int err = 0;
 
@@ -93,6 +121,15 @@ orinoco_dl_firmware(struct orinoco_private *priv,
 
         hdr = (const struct orinoco_fw_header *) fw_entry->data;
 
+        fw_err = validate_fw(hdr, fw_entry->size);
+        if (fw_err) {
+                printk(KERN_WARNING "%s: Invalid firmware image detected (%s). "
+                       "Aborting download\n",
+                       dev->name, fw_err);
+                err = -EINVAL;
+                goto abort;
+        }
+
         /* Enable aux port to allow programming */
         err = hermesi_program_init(hw, le32_to_cpu(hdr->entry_point));
         printk(KERN_DEBUG "%s: Program init returned %d\n", dev->name, err);