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    Subject[PATCH 6.0 512/862] usb: gadget: f_fs: stricter integer overflow checks
    Date
    From: Dan Carpenter <dan.carpenter@oracle.com>

    [ Upstream commit f57004b9d96755cd6a243b51c267be4016b4563c ]

    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: Sasha Levin <sashal@kernel.org>
    ---
    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 e0fa4b186ec6..36184a762527 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);

    --
    2.35.1


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