linux-kernel - [PATCH] gpu/drm: fix a -Wstringop-truncation warning

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Message-Id: <1566585426-2952-1-git-send-email-cai@lca.pw>
Date:   Fri, 23 Aug 2019 14:37:06 -0400
From:   Qian Cai <cai@....pw>
To:     daniel@...ll.ch
Cc:     maarten.lankhorst@...ux.intel.com, maxime.ripard@...tlin.com,
        sean@...rly.run, airlied@...ux.ie, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Qian Cai <cai@....pw>
Subject: [PATCH] gpu/drm: fix a -Wstringop-truncation warning

In file included from ./include/linux/bitmap.h:9,
                 from ./include/linux/cpumask.h:12,
                 from ./arch/x86/include/asm/cpumask.h:5,
                 from ./arch/x86/include/asm/msr.h:11,
                 from ./arch/x86/include/asm/processor.h:21,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/rcupdate.h:27,
                 from ./include/linux/rculist.h:11,
                 from ./include/linux/pid.h:5,
                 from ./include/linux/sched.h:14,
                 from ./include/linux/uaccess.h:5,
                 from drivers/gpu/drm/drm_property.c:24:
In function 'strncpy',
    inlined from 'drm_property_create' at
drivers/gpu/drm/drm_property.c:130:2:
./include/linux/string.h:305:9: warning: '__builtin_strncpy' specified
bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix it by using strscpy() which will always return a valid string, and
doesn't unnecessarily force the tail of the destination buffer to be
zeroed.

Signed-off-by: Qian Cai <cai@....pw>
---
 drivers/gpu/drm/drm_property.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
index 892ce636ef72..66ec2cc7a559 100644
--- a/drivers/gpu/drm/drm_property.c
+++ b/drivers/gpu/drm/drm_property.c
@@ -127,8 +127,7 @@ struct drm_property *drm_property_create(struct drm_device *dev,
 	property->num_values = num_values;
 	INIT_LIST_HEAD(&property->enum_list);
 
-	strncpy(property->name, name, DRM_PROP_NAME_LEN);
-	property->name[DRM_PROP_NAME_LEN-1] = '\0';
+	strscpy(property->name, name, DRM_PROP_NAME_LEN);
 
 	list_add_tail(&property->head, &dev->mode_config.property_list);
 
-- 
1.8.3.1