Hi,
On 3.3.2022 12.26, Mathias Nyman wrote:
> From: Anssi Hannula <anssi.hannula@xxxxxxxxxx>
>
> xhci_decode_ctrl_ctx() returns the untouched buffer as-is if both "drop"
> and "add" parameters are zero.
>
> Fix the function to return an empty string in that case.
>
> It was not immediately clear from the possible call chains whether this
> issue is currently actually triggerable or not.
>
> Note that before commit 4843b4b5ec64 ("xhci: fix even more unsafe memory
> Cc: stable@xxxxxxxxxxxxxxx
> usage in xhci tracing") the result effect in the failure case was different
> as a static buffer was used here, but the code still worked incorrectly.
You added the Cc-stable line a few lines too early above :)
> Fixes: 90d6d5731da7 ("xhci: Add tracing for input control context")
> Signed-off-by: Anssi Hannula <anssi.hannula@xxxxxxxxxx>
> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
>
> commit 4843b4b5ec64 ("xhci: fix even more unsafe memory usage in xhci tracing")
> ---
> drivers/usb/host/xhci.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 1d83ddace482..473a33ce299e 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -2468,6 +2468,8 @@ static inline const char *xhci_decode_ctrl_ctx(char *str,
> unsigned int bit;
> int ret = 0;
>
> + str[0] = '\0';
> +
> if (drop) {
> ret = sprintf(str, "Drop:");
> for_each_set_bit(bit, &drop, 32)
--
Anssi Hannula / Bitwise Oy
+358 503803997
