ata: sata_mv: Fix incorrect string length computation in mv_dump_mem()

[ Upstream commit e97eb65 ]

snprintf() returns the "number of characters which *would* be generated for
the given input", not the size *really* generated.

In order to avoid too large values for 'o' (and potential negative values
for "sizeof(linebuf) o") use scnprintf() instead of snprintf().

Note that given the "w < 4" in the for loop, the buffer can NOT
overflow, but using the *right* function is always better.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/ata/sata_mv.c

@@ -1255,8 +1255,8 @@ static void mv_dump_mem(struct device *dev, void __iomem *start, unsigned bytes)
 
 	for (b = 0; b < bytes; ) {
 		for (w = 0, o = 0; b < bytes && w < 4; w++) {
-			o += snprintf(linebuf + o, sizeof(linebuf) - o,
-				      "%08x ", readl(start + b));
+			o += scnprintf(linebuf + o, sizeof(linebuf) - o,
+				       "%08x ", readl(start + b));
 			b += sizeof(u32);
 		}
 		dev_dbg(dev, "%s: %p: %s\n",