Commit b892cb87 authored by Baoquan He's avatar Baoquan He Committed by Ingo Molnar

x86/boot/KASLR: Add checking for the offset of kernel virtual address randomization

For kernel text KASLR, the virtual address is confined to area of 1G,
[0xffffffff80000000, 0xffffffffc0000000). For the implemenataion of
virtual address randomization, we only randomize to get an offset
between 16M and 1G, then add this offset to the starting address,
0xffffffff80000000. Here 16M is the offset which is decided at linking
stage. So the amount of the local variable 'virt_addr' which respresents
the offset plus the kernel output size can not exceed KERNEL_IMAGE_SIZE.

Add a debug check for the offset. If out of bounds, print error
message and hang there.
Suggested-by: default avatarIngo Molnar <mingo@kernel.org>
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>
Link: http://lkml.kernel.org/r/1498567146-11990-2-git-send-email-bhe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 80c65fdb
...@@ -390,6 +390,8 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, ...@@ -390,6 +390,8 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
if (heap > 0x3fffffffffffUL) if (heap > 0x3fffffffffffUL)
error("Destination address too large"); error("Destination address too large");
if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
error("Destination virtual address is beyond the kernel mapping area");
#else #else
if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
error("Destination address too large"); error("Destination address too large");
......
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