[PATCH 3.2 124/152] x86, tls, ldt: Stop checking lm in LDT_empty
3.2.67-rc1 review patch. If anyone has any objections, please let me know.
--
From: Andy Lutomirski
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
Cc: torva...@linux-foundation.org
Link:
http://lkml.kernel.org/r/72a059de55e86ad5e2935c80aa91880ddf19d07c.1421954363.git.l...@amacapital.net
Signed-off-by: Thomas Gleixner
Signed-off-by: Ben Hutchings
---
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
@@ -248,7 +248,8 @@ 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&& \
@@ -258,12 +259,6 @@ 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);
--
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[PATCH 3.2 124/152] x86, tls, ldt: Stop checking lm in LDT_empty
3.2.67-rc1 review patch. If anyone has any objections, please let me know.
--
From: Andy Lutomirski l...@amacapital.net
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 l...@amacapital.net
Cc: torva...@linux-foundation.org
Link:
http://lkml.kernel.org/r/72a059de55e86ad5e2935c80aa91880ddf19d07c.1421954363.git.l...@amacapital.net
Signed-off-by: Thomas Gleixner t...@linutronix.de
Signed-off-by: Ben Hutchings b...@decadent.org.uk
---
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
@@ -248,7 +248,8 @@ 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 \
@@ -258,12 +259,6 @@ 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);
--
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