Patch "x86, tls, ldt: Stop checking lm in LDT_empty" has been added to the 3.10-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



This is a note to let you know that I've just added the patch titled

    x86, tls, ldt: Stop checking lm in LDT_empty

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-tls-ldt-stop-checking-lm-in-ldt_empty.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From e30ab185c490e9a9381385529e0fd32f0a399495 Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Date: Thu, 22 Jan 2015 11:27:58 -0800
Subject: x86, tls, ldt: Stop checking lm in LDT_empty

From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>

commit e30ab185c490e9a9381385529e0fd32f0a399495 upstream.

32-bit programs don't have an lm bit in their ABI, so they can't
reliably cause LDT_empty to return true without resorting to memset.
They shouldn't need to do this.

This should fix a longstanding, if minor, issue in all 64-bit kernels
as well as a potential regression in the TLS hardening code.

Fixes: 41bdc78544b8 x86/tls: Validate TLS entries to protect espfix
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/72a059de55e86ad5e2935c80aa91880ddf19d07c.1421954363.git.luto@xxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/include/asm/desc.h |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -251,7 +251,8 @@ static inline void native_load_tls(struc
 		gdt[GDT_ENTRY_TLS_MIN + i] = t->tls_array[i];
 }
 
-#define _LDT_empty(info)				\
+/* This intentionally ignores lm, since 32-bit apps don't have that field. */
+#define LDT_empty(info)					\
 	((info)->base_addr		== 0	&&	\
 	 (info)->limit			== 0	&&	\
 	 (info)->contents		== 0	&&	\
@@ -261,12 +262,6 @@ static inline void native_load_tls(struc
 	 (info)->seg_not_present	== 1	&&	\
 	 (info)->useable		== 0)
 
-#ifdef CONFIG_X86_64
-#define LDT_empty(info) (_LDT_empty(info) && ((info)->lm == 0))
-#else
-#define LDT_empty(info) (_LDT_empty(info))
-#endif
-
 static inline void clear_LDT(void)
 {
 	set_ldt(NULL, 0);


Patches currently in stable-queue which might be from luto@xxxxxxxxxxxxxx are

queue-3.10/x86-tls-ldt-stop-checking-lm-in-ldt_empty.patch
queue-3.10/x86-tls-interpret-an-all-zero-struct-user_desc-as-no-segment.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]