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authorAndy Lutomirski <luto@kernel.org>2015-07-31 00:31:32 +0300
committerIngo Molnar <mingo@kernel.org>2015-07-31 11:23:23 +0300
commit37868fe113ff2ba814b3b4eb12df214df555f8dc (patch)
treed1fccfadb516fbc97393b67d10385f0b7b17289e /arch/x86/include/asm/mmu.h
parentaa1acff356bbedfd03b544051f5b371746735d89 (diff)
downloadlinux-37868fe113ff2ba814b3b4eb12df214df555f8dc.tar.xz
x86/ldt: Make modify_ldt synchronous
modify_ldt() has questionable locking and does not synchronize threads. Improve it: redesign the locking and synchronize all threads' LDTs using an IPI on all modifications. This will dramatically slow down modify_ldt in multithreaded programs, but there shouldn't be any multithreaded programs that care about modify_ldt's performance in the first place. This fixes some fallout from the CVE-2015-5157 fixes. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> 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: Jan Beulich <jbeulich@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: security@kernel.org <security@kernel.org> Cc: <stable@vger.kernel.org> Cc: xen-devel <xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/4c6978476782160600471bd865b318db34c7b628.1438291540.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/mmu.h')
-rw-r--r--arch/x86/include/asm/mmu.h3
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 09b9620a73b4..364d27481a52 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -9,8 +9,7 @@
* we put the segment information here.
*/
typedef struct {
- void *ldt;
- int size;
+ struct ldt_struct *ldt;
#ifdef CONFIG_X86_64
/* True if mm supports a task running in 32 bit compatibility mode. */