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From: Sasha Levin <>
Cc: Sasha Levin <>,
	Greg Kroah-Hartman <>,, Johan Hovold <>,
Subject: [PATCH AUTOSEL 4.9 3/7] staging: greybus: loopback_test: fix potential path truncation
Date: Thu, 26 Mar 2020 19:25:22 -0400
Message-ID: <> (raw)
In-Reply-To: <>

From: Johan Hovold <>

[ Upstream commit f16023834863932f95dfad13fac3fc47f77d2f29 ]

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

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 <>
Signed-off-by: Greg Kroah-Hartman <>
Signed-off-by: Sasha Levin <>
 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 f7f4cd6fb55b3..9430f3e0162b5 100644
--- a/drivers/staging/greybus/tools/loopback_test.c
+++ b/drivers/staging/greybus/tools/loopback_test.c
@@ -646,7 +646,7 @@ 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 dummy;
 	int fds_idx = 0;
 	int i;

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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2020-03-26 23:25 ` Sasha Levin [this message]
2020-03-26 23:25 ` [PATCH AUTOSEL 4.9 4/7] staging: greybus: loopback_test: fix potential path truncations Sasha Levin

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