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Subject[027/143] [SCSI] mpt2sas: prevent heap overflows and unchecked reads
2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------
From: Dan Rosenberg <drosenberg@vsecurity.com>

commit a1f74ae82d133ebb2aabb19d181944b4e83e9960 upstream.

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.

Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Acked-by: Eric Moore <eric.moore@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/scsi/mpt2sas/mpt2sas_ctl.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
--- a/drivers/scsi/mpt2sas/mpt2sas_ctl.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
@@ -636,6 +636,13 @@ _ctl_do_mpt_command(struct MPT2SAS_ADAPT
data_out_sz = karg.data_out_size;
data_in_sz = karg.data_in_size;

+ /* 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__,
@@ -1809,7 +1816,7 @@ _ctl_diag_read_buffer(void __user *arg,
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;
@@ -1845,6 +1852,8 @@ _ctl_diag_read_buffer(void __user *arg,
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,
@@ -1852,13 +1861,23 @@ _ctl_diag_read_buffer(void __user *arg,
return -EINVAL;
}

+ if (karg.starting_offset > request_size)
+ return -EINVAL;
+
diag_data = (void *)(request_data + karg.starting_offset);
dctlprintk(ioc, printk(MPT2SAS_DEBUG_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);



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