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 strings
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-f_fs-fix-null-pointer-dereference-when-there-are-no-strings.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f0688c8b81d2ea239c3fb0b848f623b579238d99 Mon Sep 17 00:00:00 2001
From: Michal Nazarewicz <mina86@xxxxxxxxxx>
Date: Tue, 17 Jun 2014 17:47:41 +0200
Subject: usb: gadget: f_fs: fix NULL pointer dereference when there are no strings
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From: Michal Nazarewicz <mina86@xxxxxxxxxx>
commit f0688c8b81d2ea239c3fb0b848f623b579238d99 upstream.
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.
Signed-off-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/f_fs.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -1361,11 +1361,13 @@ static int functionfs_bind(struct ffs_da
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;
Patches currently in stable-queue which might be from mina86@xxxxxxxxxx are
queue-3.4/usb-gadget-f_fs-fix-null-pointer-dereference-when-there-are-no-strings.patch
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