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Subject[PATCH 3.16 070/133] scsi: qla2xxx: Fix an integer overflow in sysfs code
3.16.51-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@oracle.com>

commit e6f77540c067b48dee10f1e33678415bfcc89017 upstream.

The value of "size" comes from the user. When we add "start + size" it
could lead to an integer overflow bug.

It means we vmalloc() a lot more memory than we had intended. I believe
that on 64 bit systems vmalloc() can succeed even if we ask it to
allocate huge 4GB buffers. So we would get memory corruption and likely
a crash when we call ha->isp_ops->write_optrom() and ->read_optrom().

Only root can trigger this bug.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=194061

Fixes: b7cc176c9eb3 ("[SCSI] qla2xxx: Allow region-based flash-part accesses.")
Reported-by: shqking <shqking@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/scsi/qla2xxx/qla_attr.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/scsi/qla2xxx/qla_attr.c
+++ b/drivers/scsi/qla2xxx/qla_attr.c
@@ -396,6 +396,8 @@ qla2x00_sysfs_write_optrom_ctl(struct fi
return -EINVAL;
if (start > ha->optrom_size)
return -EINVAL;
+ if (size > ha->optrom_size - start)
+ size = ha->optrom_size - start;

mutex_lock(&ha->optrom_mutex);
switch (val) {
@@ -421,8 +423,7 @@ qla2x00_sysfs_write_optrom_ctl(struct fi
}

ha->optrom_region_start = start;
- ha->optrom_region_size = start + size > ha->optrom_size ?
- ha->optrom_size - start : size;
+ ha->optrom_region_size = start + size;

ha->optrom_state = QLA_SREADING;
ha->optrom_buffer = vmalloc(ha->optrom_region_size);
@@ -494,8 +495,7 @@ qla2x00_sysfs_write_optrom_ctl(struct fi
}

ha->optrom_region_start = start;
- ha->optrom_region_size = start + size > ha->optrom_size ?
- ha->optrom_size - start : size;
+ ha->optrom_region_size = start + size;

ha->optrom_state = QLA_SWRITING;
ha->optrom_buffer = vmalloc(ha->optrom_region_size);
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