From: Michal Nazarewicz Date: Tue, 17 Jun 2014 15:47:41 +0000 (+0200) Subject: usb: gadget: f_fs: fix NULL pointer dereference when there are no strings X-Git-Tag: upstream/snapshot3+hdmi~2209 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d4d3b27333ded534e1cab26a33b7e4f1163e8ff9;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git usb: gadget: f_fs: fix NULL pointer dereference when there are no strings 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 Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c index 2b43343..5bcf7d0 100644 --- a/drivers/usb/gadget/f_fs.c +++ b/drivers/usb/gadget/f_fs.c @@ -1227,11 +1227,13 @@ 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;