On Mon, Sep 02, 2019 at 05:30:24PM +0800, Zhenzhong Duan wrote:
> Builds kernel with "make bzImage EXTRA_CFLAGS=-Wall", gcc complains:
>
> arch/x86/boot/compressed/pgtable_64.c: In function 'paging_prepare':
> arch/x86/boot/compressed/pgtable_64.c:92:7: warning: 'new' may be used
> uninitialized in this function [-Wmaybe-uninitialized]
> new = round_down(new, PAGE_SIZE);
>
> In theory a random value of variable new may pass all the check and be
> assigned to bios_start, fixing it by assigning it an initial value.
>
> Fixes: 0a46fff2f910 ("x86/boot/compressed/64: Fix boot on machines with
> broken E820 table")
> Signed-off-by: Zhenzhong Duan <[email protected]>
> Cc: Kirill A. Shutemov <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: "H. Peter Anvin" <[email protected]>
> Cc: x86-ml <[email protected]>
> ---
> arch/x86/boot/compressed/pgtable_64.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/boot/compressed/pgtable_64.c
> b/arch/x86/boot/compressed/pgtable_64.c
> index 2faddeb..c886269 100644
> --- a/arch/x86/boot/compressed/pgtable_64.c
> +++ b/arch/x86/boot/compressed/pgtable_64.c
> @@ -72,7 +72,7 @@ static unsigned long find_trampoline_placement(void)
>
> /* Find the first usable memory region under bios_start. */
> for (i = boot_params->e820_entries - 1; i >= 0; i--) {
> - unsigned long new;
> + unsigned long new = bios_start;
>
> entry = &boot_params->e820_table[i];
>
> --
https://git.kernel.org/tip/c96e8483cb2da6695c8b8d0896fe7ae272a07b54
In the future, use tip/master when preparing fixes because it has the
latest state of the x86 tree and you won't have to duplicate effort,
like in this case.
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
