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

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commit 8eabf42ae5 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: Dave Young <dyoung@redhat.com>
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 8391c73 ("x86/KASLR: Randomize virtual address separately")
Link: http://lkml.kernel.org/r/1498567146-11990-3-git-send-email-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Baoquan He 2017-06-27 20:39:06 +08:00 • committed by Greg Kroah-Hartman

parent 15541e6416

commit b287ade87c

3 changed files with 2 additions and 7 deletions

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arch/x86/boot/compressed/kaslr.c

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4

arch/x86/boot/compressed/misc.c

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2

arch/x86/boot/compressed/misc.h

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