On Fri, Jan 18, 2019 at 11:31:52PM +0100, Laszlo Ersek wrote:
> Commit 19bcc4bc3213 ("fw_cfg: Make qemu_extra_params_fw locally",
> 2019-01-04) changed the storage duration of the "qemu_extra_params_fw"
> array from static to automatic. This broke the interface contract on the
> fw_cfg_add_file() function, which is documented as follows, in
> "include/hw/nvram/fw_cfg.h":
>
> > [...] The data referenced by the starting pointer is only linked, NOT
> > copied, into the data structure of the fw_cfg device. [...]
>
> As a result, when guest firmware fetches the "etc/boot-menu-wait" fw_cfg
> file, it now sees garbage. Fix the regression by changing the storage
> duration to allocated. (The call is reached at most once, on the realize
> path of the board-specific fw_cfg sysbus device.)
>
> While at it, clean up the name and the assignment of the object as well.
Reviewed-by: Gerd Hoffmann <kra...@redhat.com>
>
> Cc: Gerd Hoffmann <kra...@redhat.com>
> Cc: Markus Armbruster <arm...@redhat.com>
> Cc: Philippe Mathieu-Daudé <phi...@redhat.com>
> Fixes: 19bcc4bc3213e78c303ad480a7a578f62258252d
> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
> ---
> hw/nvram/fw_cfg.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 53e8e010a8b7..7fdf04adc97f 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -118,7 +118,6 @@ static void fw_cfg_bootsplash(FWCfgState *s)
> {
> const char *boot_splash_filename = NULL;
> const char *boot_splash_time = NULL;
> - uint8_t qemu_extra_params_fw[2];
> char *filename, *file_data;
> gsize file_size;
> int file_type;
> @@ -132,6 +131,8 @@ static void fw_cfg_bootsplash(FWCfgState *s)
> /* insert splash time if user configurated */
> if (boot_splash_time) {
> int64_t bst_val = qemu_opt_get_number(opts, "splash-time", -1);
> + uint16_t bst_le16;
> +
> /* validate the input */
> if (bst_val < 0 || bst_val > 0xffff) {
> error_report("splash-time is invalid,"
> @@ -139,9 +140,9 @@ static void fw_cfg_bootsplash(FWCfgState *s)
> exit(1);
> }
> /* use little endian format */
> - qemu_extra_params_fw[0] = (uint8_t)(bst_val & 0xff);
> - qemu_extra_params_fw[1] = (uint8_t)((bst_val >> 8) & 0xff);
> - fw_cfg_add_file(s, "etc/boot-menu-wait", qemu_extra_params_fw, 2);
> + bst_le16 = cpu_to_le16(bst_val);
> + fw_cfg_add_file(s, "etc/boot-menu-wait",
> + g_memdup(&bst_le16, sizeof bst_le16), sizeof
> bst_le16);
> }
>
> /* insert splash file if user configurated */
> --
> 2.19.1.3.g30247aa5d201
>
