patch "usb: gadget: f_fs: Assorted buffer overflow checks." added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    usb: gadget: f_fs: Assorted buffer overflow checks.

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 83e526f2a2fa4b2e82b6bd3ddbb26b70acfa8947 Mon Sep 17 00:00:00 2001
From: Vincent Pelletier <plr.vincent@gmail.com>
Date: Wed, 18 Jan 2017 00:57:44 +0000
Subject: usb: gadget: f_fs: Assorted buffer overflow checks.

OS descriptor head, when flagged as provided, is accessed without
checking if it fits in provided buffer. Verify length before access.
Also, there are other places where buffer length it checked
after accessing offsets which are potentially past the end. Check
buffer length before as well to fail cleanly.

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/gadget/function/f_fs.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 5490fc51638e..fd80c1b9c823 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -2269,6 +2269,8 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
 		if (len < sizeof(*d) || h->interface >= ffs->interfaces_count)
 			return -EINVAL;
 		length = le32_to_cpu(d->dwSize);
+		if (len < length)
+			return -EINVAL;
 		type = le32_to_cpu(d->dwPropertyDataType);
 		if (type < USB_EXT_PROP_UNICODE ||
 		    type > USB_EXT_PROP_UNICODE_MULTI) {
@@ -2277,6 +2279,11 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
 			return -EINVAL;
 		}
 		pnl = le16_to_cpu(d->wPropertyNameLength);
+		if (length < 14 + pnl) {
+			pr_vdebug("invalid os descriptor length: %d pnl:%d (descriptor %d)\n",
+				  length, pnl, type);
+			return -EINVAL;
+		}
 		pdl = le32_to_cpu(*(u32 *)((u8 *)data + 10 + pnl));
 		if (length != 14 + pnl + pdl) {
 			pr_vdebug("invalid os descriptor length: %d pnl:%d pdl:%d (descriptor %d)\n",
@@ -2363,6 +2370,9 @@ static int __ffs_data_got_descs(struct ffs_data *ffs,
 		}
 	}
 	if (flags & (1 << i)) {
+		if (len < 4) {
+			goto error;
+		}
 		os_descs_count = get_unaligned_le32(data);
 		data += 4;
 		len -= 4;
@@ -2435,7 +2445,8 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
 
 	ENTER();
 
-	if (unlikely(get_unaligned_le32(data) != FUNCTIONFS_STRINGS_MAGIC ||
+	if (unlikely(len < 16 ||
+		     get_unaligned_le32(data) != FUNCTIONFS_STRINGS_MAGIC ||
 		     get_unaligned_le32(data + 4) != len))
 		goto error;
 	str_count  = get_unaligned_le32(data + 8);
-- 
2.11.0