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authorJuergen Gross <jgross@suse.com>2015-08-06 10:04:38 +0200
committerIngo Molnar <mingo@kernel.org>2015-08-08 10:20:45 +0200
commit136d9d83c07c5e30ac49fc83b27e8c4842f108fc (patch)
tree3b9647ce64436c09c784a923172a5d65cdc96403 /arch/x86/kernel/step.c
parentdd2384a75d1c046faf068a6352732a204814b86d (diff)
downloadlinux-136d9d83c07c5e30ac49fc83b27e8c4842f108fc.tar.gz
x86/ldt: Correct LDT access in single stepping logic
Commit 37868fe113ff ("x86/ldt: Make modify_ldt synchronous")
introduced a new struct ldt_struct anchored at mm->context.ldt.

convert_ip_to_linear() was changed to reflect this, but indexing
into the ldt has to be changed as the pointer is no longer void *.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: <stable@vger.kernel.org> # On top of: 37868fe113ff: x86/ldt: Make modify_ldt synchronous
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@suse.de
Link: http://lkml.kernel.org/r/1438848278-12906-1-git-send-email-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/step.c')
-rw-r--r--arch/x86/kernel/step.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 6273324186ac..0ccb53a9fcd9 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -28,11 +28,11 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re
 		struct desc_struct *desc;
 		unsigned long base;
 
-		seg &= ~7UL;
+		seg >>= 3;
 
 		mutex_lock(&child->mm->context.lock);
 		if (unlikely(!child->mm->context.ldt ||
-			     (seg >> 3) >= child->mm->context.ldt->size))
+			     seg >= child->mm->context.ldt->size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {
 			desc = &child->mm->context.ldt->entries[seg];