From 0d0138ebe24b94065580bd2601f8bb7eb6152f56 Mon Sep 17 00:00:00 2001
From: Dan Rosenberg <drosenberg@vsecurity.com>
Date: Mon, 25 Jul 2011 17:11:53 -0700
Subject: xtensa: prevent arbitrary read in ptrace

Prevent an arbitrary kernel read.  Check the user pointer with access_ok()
before copying data in.

[akpm@linux-foundation.org: s/EIO/EFAULT/]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/xtensa/kernel/ptrace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index c72c9473ef99..a0d042aa2967 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -147,6 +147,9 @@ int ptrace_setxregs(struct task_struct *child, void __user *uregs)
 	elf_xtregs_t *xtregs = uregs;
 	int ret = 0;
 
+	if (!access_ok(VERIFY_READ, uregs, sizeof(elf_xtregs_t)))
+		return -EFAULT;
+
 #if XTENSA_HAVE_COPROCESSORS
 	/* Flush all coprocessors before we overwrite them. */
 	coprocessor_flush_all(ti);
-- 
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