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05 April 2024, 19:05:47 UTC
Revision 04d1d281dcfe683a53cddfab8371fc8bb302b069 authored by Andy Lutomirski on 23 February 2016, 21:19:29 UTC, committed by Ingo Molnar on 24 February 2016, 07:43:04 UTC 
x86/entry/32: Add an ASM_CLAC to entry_SYSENTER_32
 
Both before and after 5f310f739b4c ("x86/entry/32: Re-implement
SYSENTER using the new C path"), we relied on a uaccess very early
in the SYSENTER path to clear AC.  After that change, though, we can
potentially make it all the way into C code with AC set, which
enlarges the attack surface for SMAP bypass by doing SYSENTER with
AC set.

Strengthen the SMAP protection by addding the missing ASM_CLAC right
at the beginning.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3e36be110724896e32a4a1fe73bacb349d3cba94.1456262295.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent dd71a17
History
Tip revision: 04d1d281dcfe683a53cddfab8371fc8bb302b069 authored by Andy Lutomirski on 23 February 2016, 21:19:29 UTC
x86/entry/32: Add an ASM_CLAC to entry_SYSENTER_32
Tip revision: 04d1d28
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.get_maintainer.ignore -rw-r--r-- 31 bytes
.gitignore -rw-r--r-- 1.2 KB
.mailmap -rw-r--r-- 5.5 KB
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