From 769acc3656d93aaacada814939743361d284fd87 Mon Sep 17 00:00:00 2001
From: Oscar Carter <oscar.carter@gmx.com>
Date: Fri, 1 May 2020 17:51:18 +0200
Subject: [PATCH] staging: gasket: Check the return value of gasket_get_bar_index()
Git-commit: 769acc3656d93aaacada814939743361d284fd87
Patch-mainline: v5.7-rc5
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/gasket/gasket_core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
index 8e0575fcb4c8..67325fbaf760 100644
--- a/drivers/staging/gasket/gasket_core.c
+++ b/drivers/staging/gasket/gasket_core.c
@@ -925,6 +925,10 @@ 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) {
 		/*
-- 
2.16.4