This is a note to let you know that I've just added the patch titled
usb: gadget: f_fs: fix NULL pointer dereference when there are no
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 f0688c8b81d2ea239c3fb0b848f623b579238d99 Mon Sep 17 00:00:00 2001
From: Michal Nazarewicz <[email protected]>
Date: Tue, 17 Jun 2014 17:47:41 +0200
Subject: usb: gadget: f_fs: fix NULL pointer dereference when there are no
strings
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
If the descriptors do not need any strings and user space sends empty
set of strings, the ffs->stringtabs field remains NULL. Thus
*ffs->stringtabs in functionfs_bind leads to a NULL pointer
dereferenece.
The bug was introduced by commit [fd7c9a007f: “use usb_string_ids_n()”].
While at it, remove double initialisation of lang local variable in
that function.
ffs->strings_count does not need to be checked in any way since in
the above scenario it will remain zero and usb_string_ids_n() is
a no-operation when colled with 0 argument.
Cc: <[email protected]> # v2.6.36+
Signed-off-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>
---
drivers/usb/gadget/f_fs.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 74202d67f911..8598c27c7d43 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -1483,11 +1483,13 @@ static int functionfs_bind(struct ffs_data *ffs, struct
usb_composite_dev *cdev)
ffs->ep0req->context = ffs;
lang = ffs->stringtabs;
- for (lang = ffs->stringtabs; *lang; ++lang) {
- struct usb_string *str = (*lang)->strings;
- int id = first_id;
- for (; str->s; ++id, ++str)
- str->id = id;
+ if (lang) {
+ for (; *lang; ++lang) {
+ struct usb_string *str = (*lang)->strings;
+ int id = first_id;
+ for (; str->s; ++id, ++str)
+ str->id = id;
+ }
}
ffs->gadget = cdev->gadget;
--
2.0.0
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