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x86/asm: Fixup TASK_SIZE_MAX comment

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Comment says "by preventing anything executable" which is not true. Even
PROT_NONE mapping can't be installed at (1<<47 - 4096).

  mmap(0x7ffffffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM

 [ bp: Fixup to the moved location in page_64_types.h. ]

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200305181719.GA5490@avx2
This commit is contained in:
Alexey Dobriyan 2020-03-05 21:17:19 +03:00 committed by Borislav Petkov
parent f22fecaf39
commit 4f63b320af
1 changed files with 1 additions and 1 deletions
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arch/x86/include/asm/page_64_types.h
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@ -66,7 +66,7 @@
* On Intel CPUs, if a SYSCALL instruction is at the highest canonical
* address, then that syscall will enter the kernel with a
* non-canonical return address, and SYSRET will explode dangerously.
* We avoid this particular problem by preventing anything executable
* We avoid this particular problem by preventing anything
* from being mapped at the maximum canonical address.
*
* On AMD CPUs in the Ryzen family, there's a nasty bug in which the