linux-kernel - [PATCH] xtensa: prevent arbitrary read in ptrace

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Date:	Thu, 07 Jul 2011 20:03:54 -0400
From:	Dan Rosenberg <drosenberg@...curity.com>
To:	chris@...kel.net
Cc:	linux-kernel@...r.kernel.org, security@...nel.org
Subject: [PATCH] xtensa: prevent arbitrary read in ptrace

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

Signed-off-by: Dan Rosenberg <drosenberg@...curity.com>
Cc: stable@...nel.org
---
 arch/xtensa/kernel/ptrace.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index c72c947..ddce75e 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 -EIO;
+
 #if XTENSA_HAVE_COPROCESSORS
 	/* Flush all coprocessors before we overwrite them. */
 	coprocessor_flush_all(ti);


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