linux-kernel - [PATCH] i2o/i2o_config: Validate message size

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Message-Id: <1362240561-26167-1-git-send-email-linux@roeck-us.net>
Date:	Sat,  2 Mar 2013 08:09:21 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	linux-kernel@...r.kernel.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] i2o/i2o_config: Validate message size

Message size was already validated against inbound_frame_size, but that does
not guarantee that it is small enough for the buffer used to store a copy of it
on the stack.

Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
I am also not sure if the previous validation can be trusted, since the size
is read again from user space after the initial validation.

 drivers/message/i2o/i2o_config.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/message/i2o/i2o_config.c b/drivers/message/i2o/i2o_config.c
index 5451bef..aabaafc 100644
--- a/drivers/message/i2o/i2o_config.c
+++ b/drivers/message/i2o/i2o_config.c
@@ -922,6 +922,10 @@ static int i2o_cfg_passthru(unsigned long arg)
 		}
 		size = size >> 16;
 		size *= 4;
+		if (size > sizeof(rmsg)) {
+			rcode = -EFAULT;
+			goto sg_list_cleanup;
+		}
 		/* Copy in the user's I2O command */
 		if (copy_from_user(rmsg, user_msg, size)) {
 			rcode = -EFAULT;
-- 
1.7.9.7

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