Commit f57004b9 authored by Dan Carpenter's avatar Dan Carpenter Committed by Greg Kroah-Hartman
Browse files

usb: gadget: f_fs: stricter integer overflow checks 



This from static analysis.  The vla_item() takes a size and adds it to
the total.  It has a built in integer overflow check so if it encounters
an integer overflow anywhere then it records the total as SIZE_MAX.

However there is an issue here because the "lang_count*(needed_count+1)"
multiplication can overflow.  Technically the "lang_count + 1" addition
could overflow too, but that would be detected and is harmless.  Fix
both using the new size_add() and size_mul() functions.

Fixes: e6f3862f ("usb: gadget: FunctionFS: Remove VLAIS usage from gadget code")
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YxDI3lMYomE7WCjn@kili


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6690986d

drivers/usb/gadget/function/f_fs.c

+2 −2
Original line number Diff line number Diff line
@@ -2645,10 +2645,10 @@ static int __ffs_data_got_strings(struct ffs_data *ffs, 
		unsigned i = 0;

		vla_group(d);

		vla_item(d, struct usb_gadget_strings *, stringtabs,

			lang_count + 1);

			size_add(lang_count, 1));

		vla_item(d, struct usb_gadget_strings, stringtab, lang_count);

		vla_item(d, struct usb_string, strings,

			lang_count*(needed_count+1));

			size_mul(lang_count, (needed_count + 1)));



		char *vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL);