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| author | Michal Nazarewicz <mina86@mina86.com> | 2014-06-17 17:47:41 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2014-08-06 18:07:32 +0100 |
| commit | 9919dc4b14683d1edefac5d13503046920776e72 (patch) | |
| tree | 878f8361928d2047db123238213dad25c0991d44 | |
| parent | 23f2204d5d91dc5c383fbc3707cc0694688e04c2 (diff) | |
| download | lwn-9919dc4b14683d1edefac5d13503046920776e72.tar.gz lwn-9919dc4b14683d1edefac5d13503046920776e72.zip | |
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 <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/usb/gadget/f_fs.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c index 0e641a1eabd0..c635c4c22284 100644 --- a/drivers/usb/gadget/f_fs.c +++ b/drivers/usb/gadget/f_fs.c @@ -1376,11 +1376,13 @@ 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; |