From f57004b9d96755cd6a243b51c267be4016b4563c Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 1 Sep 2022 17:59:42 +0300
Subject: [PATCH] usb: gadget: f_fs: stricter integer overflow checks
Git-commit: f57004b9d96755cd6a243b51c267be4016b4563c
References: git-fixes
Patch-mainline: v6.1-rc1
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: e6f3862fa1ec ("usb: gadget: FunctionFS: Remove VLAIS usage from gadget code")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YxDI3lMYomE7WCjn@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/usb/gadget/function/f_fs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 98dc2291e9a1..73dc10a77cde 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -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);
--
2.35.3