[PATCH] drivers/scsi/mpt2sas: prevent heap overflows and unchecked reads

[PATCH] drivers/scsi/mpt2sas: prevent heap overflows and unchecked reads

[Dan Rosenberg]

At two points in handling device ioctls via /dev/mpt2ctl, user-supplied
length values are used to copy data from userspace into heap buffers
without bounds checking, allowing controllable heap corruption and
subsequently privilege escalation.

Additionally, user-supplied values are used to determine the size of a
copy_to_user() as well as the offset into the buffer to be read, with no
bounds checking, allowing users to read arbitrary kernel memory.

Compile-tested only.  Thanks to Eric Moore for suggestions on how to fix
this.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
---
 drivers/scsi/mpt2sas/mpt2sas_ctl.c |   23 +++++++++++++++++++++--
 1 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/mpt2sas/mpt2sas_ctl.c b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
index e92b77a..3834c95 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_ctl.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
@@ -688,6 +688,13 @@ _ctl_do_mpt_command(struct MPT2SAS_ADAPTER *ioc,
 		goto out;
 	}
 
+	/* Check for overflow and wraparound */
+	if (karg.data_sge_offset * 4 > ioc->request_sz ||
+	    karg.data_sge_offset > (UINT_MAX / 4)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	/* copy in request message frame from user */
 	if (copy_from_user(mpi_request, mf, karg.data_sge_offset*4)) {
 		printk(KERN_ERR "failure at %s:%d/%s()!\n", __FILE__, __LINE__,
@@ -1963,7 +1970,7 @@ _ctl_diag_read_buffer(void __user *arg, enum block_state state)
 	Mpi2DiagBufferPostReply_t *mpi_reply;
 	int rc, i;
 	u8 buffer_type;
-	unsigned long timeleft;
+	unsigned long timeleft, request_size, copy_size;
 	u16 smid;
 	u16 ioc_status;
 	u8 issue_reset = 0;
@@ -1999,6 +2006,8 @@ _ctl_diag_read_buffer(void __user *arg, enum block_state state)
 		return -ENOMEM;
 	}
 
+	request_size = ioc->diag_buffer_sz[buffer_type];
+
 	if ((karg.starting_offset % 4) || (karg.bytes_to_read % 4)) {
 		printk(MPT2SAS_ERR_FMT "%s: either the starting_offset "
 		    "or bytes_to_read are not 4 byte aligned\n", ioc->name,
@@ -2006,13 +2015,23 @@ _ctl_diag_read_buffer(void __user *arg, enum block_state state)
 		return -EINVAL;
 	}
 
+	if (karg.starting_offset > request_size)
+		return -EINVAL;
+
 	diag_data = (void *)(request_data + karg.starting_offset);
 	dctlprintk(ioc, printk(MPT2SAS_INFO_FMT "%s: diag_buffer(%p), "
 	    "offset(%d), sz(%d)\n", ioc->name, __func__,
 	    diag_data, karg.starting_offset, karg.bytes_to_read));
 
+	/* Truncate data on requests that are too large */
+	if ((diag_data + karg.bytes_to_read < diag_data) ||
+	    (diag_data + karg.bytes_to_read > request_data + request_size))
+		copy_size = request_size - karg.starting_offset;
+	else
+		copy_size = karg.bytes_to_read;
+
 	if (copy_to_user((void __user *)uarg->diagnostic_data,
-	    diag_data, karg.bytes_to_read)) {
+	    diag_data, copy_size)) {
 		printk(MPT2SAS_ERR_FMT "%s: Unable to write "
 		    "mpt_diag_read_buffer_t data @ %p\n", ioc->name,
 		    __func__, diag_data);

RE: [PATCH] drivers/scsi/mpt2sas: prevent heap overflows and unchecked reads

[Desai, Kashyap]

This patch has been tested by Eric Moore and it works fine.

Please consider this patch "Acked-by: Eric Moore <eric.moore@lsi.com>" 

Thanks, Kashyap

> -----Original Message-----
> From: Dan Rosenberg [mailto:drosenberg@vsecurity.com]
> Sent: Tuesday, April 05, 2011 10:16 PM
> To: Moore, Eric; james.bottomley@suse.de; Desai, Kashyap
> Cc: security@kernel.org; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Subject: [PATCH] drivers/scsi/mpt2sas: prevent heap overflows and
> unchecked reads
> 
> At two points in handling device ioctls via /dev/mpt2ctl, user-supplied
> length values are used to copy data from userspace into heap buffers
> without bounds checking, allowing controllable heap corruption and
> subsequently privilege escalation.
> 
> Additionally, user-supplied values are used to determine the size of a
> copy_to_user() as well as the offset into the buffer to be read, with
> no
> bounds checking, allowing users to read arbitrary kernel memory.
> 
> Compile-tested only.  Thanks to Eric Moore for suggestions on how to
> fix
> this.
> 
> Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
> Cc: stable@kernel.org
> ---
>  drivers/scsi/mpt2sas/mpt2sas_ctl.c |   23 +++++++++++++++++++++--
>  1 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/mpt2sas/mpt2sas_ctl.c
> b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
> index e92b77a..3834c95 100644
> --- a/drivers/scsi/mpt2sas/mpt2sas_ctl.c
> +++ b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
> @@ -688,6 +688,13 @@ _ctl_do_mpt_command(struct MPT2SAS_ADAPTER *ioc,
>  		goto out;
>  	}
> 
> +	/* Check for overflow and wraparound */
> +	if (karg.data_sge_offset * 4 > ioc->request_sz ||
> +	    karg.data_sge_offset > (UINT_MAX / 4)) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
>  	/* copy in request message frame from user */
>  	if (copy_from_user(mpi_request, mf, karg.data_sge_offset*4)) {
>  		printk(KERN_ERR "failure at %s:%d/%s()!\n", __FILE__,
> __LINE__,
> @@ -1963,7 +1970,7 @@ _ctl_diag_read_buffer(void __user *arg, enum
> block_state state)
>  	Mpi2DiagBufferPostReply_t *mpi_reply;
>  	int rc, i;
>  	u8 buffer_type;
> -	unsigned long timeleft;
> +	unsigned long timeleft, request_size, copy_size;
>  	u16 smid;
>  	u16 ioc_status;
>  	u8 issue_reset = 0;
> @@ -1999,6 +2006,8 @@ _ctl_diag_read_buffer(void __user *arg, enum
> block_state state)
>  		return -ENOMEM;
>  	}
> 
> +	request_size = ioc->diag_buffer_sz[buffer_type];
> +
>  	if ((karg.starting_offset % 4) || (karg.bytes_to_read % 4)) {
>  		printk(MPT2SAS_ERR_FMT "%s: either the starting_offset "
>  		    "or bytes_to_read are not 4 byte aligned\n", ioc->name,
> @@ -2006,13 +2015,23 @@ _ctl_diag_read_buffer(void __user *arg, enum
> block_state state)
>  		return -EINVAL;
>  	}
> 
> +	if (karg.starting_offset > request_size)
> +		return -EINVAL;
> +
>  	diag_data = (void *)(request_data + karg.starting_offset);
>  	dctlprintk(ioc, printk(MPT2SAS_INFO_FMT "%s: diag_buffer(%p), "
>  	    "offset(%d), sz(%d)\n", ioc->name, __func__,
>  	    diag_data, karg.starting_offset, karg.bytes_to_read));
> 
> +	/* Truncate data on requests that are too large */
> +	if ((diag_data + karg.bytes_to_read < diag_data) ||
> +	    (diag_data + karg.bytes_to_read > request_data +
> request_size))
> +		copy_size = request_size - karg.starting_offset;
> +	else
> +		copy_size = karg.bytes_to_read;
> +
>  	if (copy_to_user((void __user *)uarg->diagnostic_data,
> -	    diag_data, karg.bytes_to_read)) {
> +	    diag_data, copy_size)) {
>  		printk(MPT2SAS_ERR_FMT "%s: Unable to write "
>  		    "mpt_diag_read_buffer_t data @ %p\n", ioc->name,
>  		    __func__, diag_data);
> 
> 
>