drivers/leds/leds-lp5521.c: fix potential buffer overflow

The code doesn't check first sscanf() return value.  If first sscanf()
failed then c contains some garbage.  It might lead to reading
uninitialised stack data in the second sscanf() call.
Signed-off-by: NVasiliy Kulikov <segoon@openwall.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/leds/leds-lp5521.c

@@ -373,6 +373,8 @@ static int lp5521_do_store_load(struct lp5521_engine *engine,
 	while ((offset < len - 1) && (i < LP5521_PROGRAM_LENGTH)) {
 		/* separate sscanfs because length is working only for %s */
 		ret = sscanf(buf + offset, "%2s%n ", c, &nrchars);
+		if (ret != 2)
+			goto fail;
 		ret = sscanf(c, "%2x", &cmd);
 		if (ret != 1)
 			goto fail;