linux-kernel - [PATCH] usb: musb: Fix a few off-by-one lengths

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Date:	Thu, 27 Nov 2014 22:25:45 +0100
From:	Rasmus Villemoes <linux@...musvillemoes.dk>
To:	Felipe Balbi <balbi@...com>
Cc:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] usb: musb: Fix a few off-by-one lengths

!strncmp(buf, "force host", 9) is true if and only if buf starts with
"force hos". This was obviously not what was intended. The same error
exists for "force full-speed", "force high-speed" and "test
packet". Using strstarts avoids the error-prone hardcoding of the
prefix length.

For consistency, also change the other occurences of the !strncmp
idiom.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
Strictly speaking this is a user-visible change since buf came from
userspace. I can't believe anybody cares, though.

 drivers/usb/musb/musb_cppi41.c  |  4 ++--
 drivers/usb/musb/musb_debugfs.c | 16 ++++++++--------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c
index 5a9b977..560d54f 100644
--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -620,9 +620,9 @@ static int cppi41_dma_controller_start(struct cppi41_dma_controller *controller)
 		ret = of_property_read_string_index(np, "dma-names", i, &str);
 		if (ret)
 			goto err;
-		if (!strncmp(str, "tx", 2))
+		if (strstarts(str, "tx"))
 			is_tx = 1;
-		else if (!strncmp(str, "rx", 2))
+		else if (strstarts(str, "rx"))
 			is_tx = 0;
 		else {
 			dev_err(dev, "Wrong dmatype %s\n", str);
diff --git a/drivers/usb/musb/musb_debugfs.c b/drivers/usb/musb/musb_debugfs.c
index 4c21679..05d1b20 100644
--- a/drivers/usb/musb/musb_debugfs.c
+++ b/drivers/usb/musb/musb_debugfs.c
@@ -194,30 +194,30 @@ static ssize_t musb_test_mode_write(struct file *file,
 	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
 		return -EFAULT;
 
-	if (!strncmp(buf, "force host", 9))
+	if (strstarts(buf, "force host"))
 		test = MUSB_TEST_FORCE_HOST;
 
-	if (!strncmp(buf, "fifo access", 11))
+	if (strstarts(buf, "fifo access"))
 		test = MUSB_TEST_FIFO_ACCESS;
 
-	if (!strncmp(buf, "force full-speed", 15))
+	if (strstarts(buf, "force full-speed"))
 		test = MUSB_TEST_FORCE_FS;
 
-	if (!strncmp(buf, "force high-speed", 15))
+	if (strstarts(buf, "force high-speed"))
 		test = MUSB_TEST_FORCE_HS;
 
-	if (!strncmp(buf, "test packet", 10)) {
+	if (strstarts(buf, "test packet")) {
 		test = MUSB_TEST_PACKET;
 		musb_load_testpacket(musb);
 	}
 
-	if (!strncmp(buf, "test K", 6))
+	if (strstarts(buf, "test K"))
 		test = MUSB_TEST_K;
 
-	if (!strncmp(buf, "test J", 6))
+	if (strstarts(buf, "test J"))
 		test = MUSB_TEST_J;
 
-	if (!strncmp(buf, "test SE0 NAK", 12))
+	if (strstarts(buf, "test SE0 NAK"))
 		test = MUSB_TEST_SE0_NAK;
 
 	musb_writeb(musb->mregs, MUSB_TESTMODE, test);
-- 
2.0.4

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