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module/retpoline: Warn about missing retpoline in module
authorAndi Kleen <ak@linux.intel.com>
Thu, 25 Jan 2018 23:50:28 +0000 (15:50 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 7 Feb 2018 19:12:18 +0000 (11:12 -0800)
commit86b5b1eb18aa49eedff2c9a9087fc48d03099844
tree4fe58a69192864e42bbc8b3e5be58ead8fbb6cb2
parentc927726674c7dfe42e8de585b70ffbd9ec775fc6
module/retpoline: Warn about missing retpoline in module

commit caf7501a1b4ec964190f31f9c3f163de252273b8

There's a risk that a kernel which has full retpoline mitigations becomes
vulnerable when a module gets loaded that hasn't been compiled with the
right compiler or the right option.

To enable detection of that mismatch at module load time, add a module info
string "retpoline" at build time when the module was compiled with
retpoline support. This only covers compiled C source, but assembler source
or prebuilt object files are not checked.

If a retpoline enabled kernel detects a non retpoline protected module at
load time, print a warning and report it in the sysfs vulnerability file.

[ tglx: Massaged changelog ]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: gregkh@linuxfoundation.org
Cc: torvalds@linux-foundation.org
Cc: jeyu@kernel.org
Cc: arjan@linux.intel.com
Link: https://lkml.kernel.org/r/20180125235028.31211-1-andi@firstfloor.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/x86/kernel/cpu/bugs.c
include/linux/module.h
kernel/module.c
scripts/mod/modpost.c