x86/boot/compressed/64: Fix missing initialization in find_trampoline_placement()

[ Upstream commit c96e8483cb2da6695c8b8d0896fe7ae272a07b54 ]

Gustavo noticed that 'new' can be left uninitialized if 'bios_start'
happens to be less or equal to 'entry->addr + entry->size'.

Initialize the variable at the begin of the iteration to the current value
of 'bios_start'.

Fixes: 0a46fff2f910 ("x86/boot/compressed/64: Fix boot on machines with broken E820 table")
Reported-by: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190826133326.7cxb4vbmiawffv2r@box
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index f0537a1f7fc25d5249df10517476eaa4218ee757..76e1edf5bf12a0ffec3401fef160a2c5fe26e37f 100644 (file)
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -73,7 +73,7 @@ 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];