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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-19 13:18:31 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-19 13:18:31 -0800
commit1092b596a56b6ac5fa3154dc75bfcbb6f27ac757 (patch)
treea804de50bae89bba47aaa414e6a4fb033da0dd94
parent88a57667f2990f00b019d46c8426441c9e516d51 (diff)
parent3fb2f4237bb452eb4e98f6a5dbd5a445b4fed9d0 (diff)
downloadlinux-1092b596a56b6ac5fa3154dc75bfcbb6f27ac757.tar.bz2
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Ingo Molnar: "This contains a single TLS ABI validation fix from Andy Lutomirski" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/tls: Don't validate lm in set_thread_area() after all
-rw-r--r--arch/x86/include/uapi/asm/ldt.h7
-rw-r--r--arch/x86/kernel/tls.c6
2 files changed, 7 insertions, 6 deletions
diff --git a/arch/x86/include/uapi/asm/ldt.h b/arch/x86/include/uapi/asm/ldt.h
index 46727eb37bfe..6e1aaf73852a 100644
--- a/arch/x86/include/uapi/asm/ldt.h
+++ b/arch/x86/include/uapi/asm/ldt.h
@@ -28,6 +28,13 @@ struct user_desc {
unsigned int seg_not_present:1;
unsigned int useable:1;
#ifdef __x86_64__
+ /*
+ * Because this bit is not present in 32-bit user code, user
+ * programs can pass uninitialized values here. Therefore, in
+ * any context in which a user_desc comes from a 32-bit program,
+ * the kernel must act as though lm == 0, regardless of the
+ * actual value.
+ */
unsigned int lm:1;
#endif
};
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index 3e551eee87b9..4e942f31b1a7 100644
--- a/arch/x86/kernel/tls.c
+++ b/arch/x86/kernel/tls.c
@@ -55,12 +55,6 @@ static bool tls_desc_okay(const struct user_desc *info)
if (info->seg_not_present)
return false;
-#ifdef CONFIG_X86_64
- /* The L bit makes no sense for data. */
- if (info->lm)
- return false;
-#endif
-
return true;
}