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From: Johan Hovold <johan@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: devel@driverdev.osuosl.org, Alex Elder <elder@kernel.org>,
	Axel Haslam <ahaslam@baylibre.com>,
	Johan Hovold <johan@kernel.org>,
	linux-kernel@vger.kernel.org, greybus-dev@lists.linaro.org
Subject: [PATCH 2/3] staging: greybus: loopback_test: fix potential path truncation
Date: Thu, 12 Mar 2020 12:01:50 +0100
Message-ID: <20200312110151.22028-3-johan@kernel.org> (raw)
In-Reply-To: <20200312110151.22028-1-johan@kernel.org>

Newer GCC warns about a possible truncation of a generated sysfs path
name as we're concatenating a directory path with a file name and
placing the result in a buffer that is half the size of the maximum
length of the directory path (which is user controlled).

loopback_test.c: In function 'open_poll_files':
loopback_test.c:651:31: warning: '%s' directive output may be truncated writing up to 511 bytes into a region of size 255 [-Wformat-truncation=]
  651 |   snprintf(buf, sizeof(buf), "%s%s", dev->sysfs_entry, "iteration_count");
      |                               ^~
loopback_test.c:651:3: note: 'snprintf' output between 16 and 527 bytes into a destination of size 255
  651 |   snprintf(buf, sizeof(buf), "%s%s", dev->sysfs_entry, "iteration_count");
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by making sure the buffer is large enough the concatenated
strings.

Fixes: 6b0658f68786 ("greybus: tools: Add tools directory to greybus repo and add loopback")
Fixes: 9250c0ee2626 ("greybus: Loopback_test: use poll instead of inotify")
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/staging/greybus/tools/loopback_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/greybus/tools/loopback_test.c b/drivers/staging/greybus/tools/loopback_test.c
index 41e1820d9ac9..d38bb4fbd6b9 100644
--- a/drivers/staging/greybus/tools/loopback_test.c
+++ b/drivers/staging/greybus/tools/loopback_test.c
@@ -637,7 +637,7 @@ int find_loopback_devices(struct loopback_test *t)
 static int open_poll_files(struct loopback_test *t)
 {
 	struct loopback_device *dev;
-	char buf[MAX_STR_LEN];
+	char buf[MAX_SYSFS_PATH + MAX_STR_LEN];
 	char dummy;
 	int fds_idx = 0;
 	int i;
-- 
2.24.1

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Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-12 11:01 [PATCH 0/3] staging: greybus: loopback_test: fix build breakage Johan Hovold
2020-03-12 11:01 ` [PATCH 1/3] staging: greybus: loopback_test: fix poll-mask " Johan Hovold
2020-03-12 11:01 ` Johan Hovold [this message]
2020-03-12 11:01 ` [PATCH 3/3] staging: greybus: loopback_test: fix potential path truncations Johan Hovold

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