• Josh Poimboeuf's avatar
    x86/dumpstack: Remove raw stack dump · 0ee1dd9f
    Josh Poimboeuf authored
    For mostly historical reasons, the x86 oops dump shows the raw stack
    values:
    
      ...
      [registers]
      Stack:
       ffff880079af7350 ffff880079905400 0000000000000000 ffffc900008f3ae0
       ffffffffa0196610 0000000000000001 00010000ffffffff 0000000087654321
       0000000000000002 0000000000000000 0000000000000000 0000000000000000
      Call Trace:
      ...
    
    This seems to be an artifact from long ago, and probably isn't needed
    anymore.  It generally just adds noise to the dump, and it can be
    actively harmful because it leaks kernel addresses.
    
    Linus says:
    
      "The stack dump actually goes back to forever, and it used to be
       useful back in 1992 or so. But it used to be useful mainly because
       stacks were simpler and we didn't have very good call traces anyway. I
       definitely remember having used them - I just do not remember having
       used them in the last ten+ years.
    
       Of course, it's still true that if you can trigger an oops, you've
       likely already lost the security game, but since the stack dump is so
       useless, let's aim to just remove it and make games like the above
       harder."
    
    This also removes the related 'kstack=' cmdline option and the
    'kstack_depth_to_print' sysctl.
    Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/e83bd50df52d8fe88e94d2566426ae40d813bf8f.1477405374.git.jpoimboe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    0ee1dd9f
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