staging: gasket: Check the return value of gasket_get_bar_index()

commit 769acc3656d93aaacada814939743361d284fd87 upstream.

Check the return value of gasket_get_bar_index function as it can return
a negative one (-EINVAL). If this happens, a negative index is used in
the "gasket_dev->bar_data" array.

Addresses-Coverity-ID: 1438542 ("Negative array index read")
Fixes: 9a69f5087ccc2 ("drivers/staging: Gasket driver framework + Apex driver")
Signed-off-by: Oscar Carter <oscar.carter@gmx.com>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Richard Yeh <rcy@google.com>
Link: https://lore.kernel.org/r/20200501155118.13380-1-oscar.carter@gmx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
index 13179f0..6f9c0d1 100644 (file)
--- a/drivers/staging/gasket/gasket_core.c
+++ b/drivers/staging/gasket/gasket_core.c
@@ -926,6 +926,10 @@ do_map_region(const struct gasket_dev *gasket_dev, struct vm_area_struct *vma,
                gasket_get_bar_index(gasket_dev,
                                     (vma->vm_pgoff << PAGE_SHIFT) +
                                     driver_desc->legacy_mmap_address_offset);
+
+       if (bar_index < 0)
+               return DO_MAP_REGION_INVALID;
+
        phys_base = gasket_dev->bar_data[bar_index].phys_base + phys_offset;
        while (mapped_bytes < map_length) {
                /*