[PATCH] wifi: libertas_tf: validate firmware block extents

[Pengpeng Hou]

check_fwfile_format() reads each block header and trusts its data length
before proving that both fit in the firmware image. A truncated header or
oversized block can therefore pass malformed extents to the download path.

Require the remaining image to contain the complete header and payload
before accepting each block.

Fixes: c305a19a0d0a ("libertas_tf: usb specific functions")
Signed-off-by: Pengpeng Hou <pengpeng at iscas.ac.cn>
---
 drivers/net/wireless/marvell/libertas_tf/if_usb.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/libertas_tf/if_usb.c b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
index b85c6d783bf7b..b9d1a33bddfce 100644
--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
@@ -769,10 +769,18 @@ static int check_fwfile_format(const u8 *data, u32 totlen)
 	exit = len = 0;
 
 	do {
-		struct fwheader *fwh = (void *) data;
+		struct fwheader *fwh;
+
+		if (totlen - len < sizeof(*fwh))
+			break;
+
+		fwh = (void *)data;
 
 		bincmd = le32_to_cpu(fwh->dnldcmd);
 		blksize = le32_to_cpu(fwh->datalength);
+		if (blksize > totlen - len - sizeof(*fwh))
+			break;
+
 		switch (bincmd) {
 		case FW_HAS_DATA_TO_RECV:
 			offset = sizeof(struct fwheader) + blksize;

base-commit: 08dbfad3f5040f5bdb6c529da20d6d4e81fefd72
-- 
2.50.1