linux-kernel - [PATCH] staging: gasket: Check the return value of gasket_get_bar

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Date:   Fri,  1 May 2020 17:51:18 +0200
From:   Oscar Carter <oscar.carter@....com>
To:     Rob Springer <rspringer@...gle.com>,
        Todd Poynor <toddpoynor@...gle.com>,
        Ben Chan <benchan@...omium.org>, Richard Yeh <rcy@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Simon Que <sque@...omium.org>,
        John Joseph <jnjoseph@...gle.com>, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, Oscar Carter <oscar.carter@....com>
Subject: [PATCH] staging: gasket: Check the return value of gasket_get_bar_index()

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@....com>
---
 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) {
 		/*
--
2.20.1