Commit cc6b8fbc authored by Baoquan He's avatar Baoquan He Committed by Greg Kroah-Hartman

x86/boot/KASLR: Fix kexec crash due to 'virt_addr' calculation bug

commit 8eabf42a upstream.

Kernel text KASLR is separated into physical address and virtual
address randomization. And for virtual address randomization, we
only randomiza to get an offset between 16M and KERNEL_IMAGE_SIZE.
So the initial value of 'virt_addr' should be LOAD_PHYSICAL_ADDR,
but not the original kernel loading address 'output'.

The bug will cause kernel boot failure if kernel is loaded at a different
position than the address, 16M, which is decided at compiled time.
Kexec/kdump is such practical case.

To fix it, just assign LOAD_PHYSICAL_ADDR to virt_addr as initial
value.
Tested-by: default avatarDave Young <dyoung@redhat.com>
Signed-off-by: default avatarBaoquan He <bhe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 8391c73c ("x86/KASLR: Randomize virtual address separately")
Link: http://lkml.kernel.org/r/1498567146-11990-3-git-send-email-bhe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 875cfdbe
...@@ -564,9 +564,6 @@ void choose_random_location(unsigned long input, ...@@ -564,9 +564,6 @@ void choose_random_location(unsigned long input,
{ {
unsigned long random_addr, min_addr; unsigned long random_addr, min_addr;
/* By default, keep output position unchanged. */
*virt_addr = *output;
if (cmdline_find_option_bool("nokaslr")) { if (cmdline_find_option_bool("nokaslr")) {
warn("KASLR disabled: 'nokaslr' on cmdline."); warn("KASLR disabled: 'nokaslr' on cmdline.");
return; return;
......
...@@ -338,7 +338,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, ...@@ -338,7 +338,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
unsigned long output_len) unsigned long output_len)
{ {
const unsigned long kernel_total_size = VO__end - VO__text; const unsigned long kernel_total_size = VO__end - VO__text;
unsigned long virt_addr = (unsigned long)output; unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
/* Retain x86 boot parameters pointer passed from startup_32/64. */ /* Retain x86 boot parameters pointer passed from startup_32/64. */
boot_params = rmode; boot_params = rmode;
...@@ -397,7 +397,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, ...@@ -397,7 +397,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
#ifndef CONFIG_RELOCATABLE #ifndef CONFIG_RELOCATABLE
if ((unsigned long)output != LOAD_PHYSICAL_ADDR) if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
error("Destination address does not match LOAD_PHYSICAL_ADDR"); error("Destination address does not match LOAD_PHYSICAL_ADDR");
if ((unsigned long)output != virt_addr) if (virt_addr != LOAD_PHYSICAL_ADDR)
error("Destination virtual address changed when not relocatable"); error("Destination virtual address changed when not relocatable");
#endif #endif
......
...@@ -81,8 +81,6 @@ static inline void choose_random_location(unsigned long input, ...@@ -81,8 +81,6 @@ static inline void choose_random_location(unsigned long input,
unsigned long output_size, unsigned long output_size,
unsigned long *virt_addr) unsigned long *virt_addr)
{ {
/* No change from existing output location. */
*virt_addr = *output;
} }
#endif #endif
......
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