linux-kernel - [PATCH] drm/i915: Fix a crash in shmem_pin

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Date:   Fri, 23 Oct 2020 14:34:01 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Christoph Hellwig <hch@....de>
Cc:     Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Auld <matthew.auld@...el.com>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] drm/i915: Fix a crash in shmem_pin_map() error handling

There is a signedness bug in shmem_pin_map() error handling because "i"
is unsigned.  The "while (--i >= 0)" will loop forever until the system
crashes.

Fixes: bfed6708d6c9 ("drm/i915: use vmap in shmem_pin_map")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/gpu/drm/i915/gt/shmem_utils.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/shmem_utils.c b/drivers/gpu/drm/i915/gt/shmem_utils.c
index f011ea42487e..7eb542018219 100644
--- a/drivers/gpu/drm/i915/gt/shmem_utils.c
+++ b/drivers/gpu/drm/i915/gt/shmem_utils.c
@@ -52,8 +52,9 @@ struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
 void *shmem_pin_map(struct file *file)
 {
 	struct page **pages;
-	size_t n_pages, i;
+	size_t n_pages;
 	void *vaddr;
+	int i;
 
 	n_pages = file->f_mapping->host->i_size >> PAGE_SHIFT;
 	pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
-- 
2.28.0