[syslinux] [PATCH] load_linux: relocate protected-mode code as intended

Scot Doyle lkml14 at scotdoyle.com
Sat Feb 7 19:46:28 PST 2015

If the kernel is relocatable and the protected mode code will not fit
in the initially determined location, that code will be moved to the
next available location. However, beginning with commit 8f470e7b, the
code is moved to the initially determined location instead of the next
available location because prot_mode_base is no longer updated to the
correct location. Since whdr->code32_start is updated, it is pointing
to the wrong execution start location, random code is executed and
the machine is rebooted.

Restore the old behavior by assigning prot_mode_base the value of
base. Tested on a machine that exposed this behavior.

Signed-off-by: Scot Doyle <lkml14 at scotdoyle.com>
This patch may be applied in addition to "load_linux: correct a type"

 com32/lib/syslinux/load_linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/com32/lib/syslinux/load_linux.c b/com32/lib/syslinux/load_linux.c
index 06ae2a9..5cecef4 100644
--- a/com32/lib/syslinux/load_linux.c
+++ b/com32/lib/syslinux/load_linux.c
@@ -323,6 +323,7 @@ int bios_boot_linux(void *kernel_buf, size_t kernel_size,
     whdr->code32_start += base - prot_mode_base;
+    prot_mode_base = base;
     /* Real mode code */
     if (syslinux_memmap_find(amap, &real_mode_base,

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