[PATCH 4.11 172/197] firmware: ti_sci: fix strncat length check

[Greg Kroah-Hartman]

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@xxxxxxxx>

commit 76cefef8e838304a71725a0b5007c375619d78fb upstream.

gcc-7 notices that the length we pass to strncat is wrong:

drivers/firmware/ti_sci.c: In function 'ti_sci_probe':
drivers/firmware/ti_sci.c:204:32: error: specified bound 50 equals the size of the destination [-Werror=stringop-overflow=]

Instead of the total length, we must pass the length of the
remaining space here.

Fixes: aa276781a64a ("firmware: Add basic support for TI System Control Interface (TI-SCI) protocol")
Acked-by: Nishanth Menon <nm@xxxxxx>
Acked-by: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/firmware/ti_sci.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c
@@ -202,7 +202,8 @@ static int ti_sci_debugfs_create(struct
 	info->debug_buffer[info->debug_region_size] = 0;
 
 	info->d = debugfs_create_file(strncat(debug_name, dev_name(dev),
-					      sizeof(debug_name)),
+					      sizeof(debug_name) -
+					      sizeof("ti_sci_debug@")),
 				      0444, NULL, info, &ti_sci_debug_fops);
 	if (IS_ERR(info->d))
 		return PTR_ERR(info->d);