diff options
| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2016-10-25 09:51:13 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-10-25 18:40:37 +0200 |
| commit | 0ee1dd9f5e7eae4e55f95935b72d4beecb03de9c (patch) | |
| tree | d552e8dc63d8daac8e472accff99b6710b57348e /Documentation/x86 | |
| parent | bb5e5ce545f2031c96f7901cd8d1698ea3ca4c9c (diff) | |
x86/dumpstack: Remove raw stack dump
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: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh 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.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/x86')
| -rw-r--r-- | Documentation/x86/x86_64/boot-options.txt | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 0965a71f9942..61b611e9eeaf 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -277,10 +277,6 @@ IOMMU (input/output memory management unit) space might stop working. Use this option if you have devices that are accessed from userspace directly on some PCI host bridge. -Debugging - - kstack=N Print N words from the kernel stack in oops dumps. - Miscellaneous nogbpages |