[PATCH AUTOSEL 4.9 3/7] staging: greybus: loopback_test: fix potential path truncation

[PATCH AUTOSEL 4.9 3/7] staging: greybus: loopback_test: fix potential path truncation

[Sasha Levin]

From: Johan Hovold <johan@kernel.org>

[ 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
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>
Link: https://lore.kernel.org/r/20200312110151.22028-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@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 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 buf[MAX_SYSFS_PATH + MAX_STR_LEN];
 	char dummy;
 	int fds_idx = 0;
 	int i;
-- 
2.20.1

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[PATCH AUTOSEL 4.9 4/7] staging: greybus: loopback_test: fix potential path truncations

[Sasha Levin]

From: Johan Hovold <johan@kernel.org>

[ Upstream commit ae62cf5eb2792d9a818c2d93728ed92119357017 ]

Newer GCC warns about possible truncations of two generated path names as
we're concatenating the configurable sysfs and debugfs path prefixes
with a filename and placing the results in buffers of the same size as
the maximum length of the prefixes.

	snprintf(d->name, MAX_STR_LEN, "gb_loopback%u", dev_id);

	snprintf(d->sysfs_entry, MAX_SYSFS_PATH, "%s%s/",
		 t->sysfs_prefix, d->name);

	snprintf(d->debugfs_entry, MAX_SYSFS_PATH, "%sraw_latency_%s",
		 t->debugfs_prefix, d->name);

Fix this by separating the maximum path length from the maximum prefix
length and reducing the latter enough to fit the generated strings.

Note that we also need to reduce the device-name buffer size as GCC
isn't smart enough to figure out that we ever only used MAX_STR_LEN
bytes of it.

Fixes: 6b0658f68786 ("greybus: tools: Add tools directory to greybus repo and add loopback")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200312110151.22028-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/staging/greybus/tools/loopback_test.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/greybus/tools/loopback_test.c b/drivers/staging/greybus/tools/loopback_test.c
index 9430f3e0162b5..8d2678b22c360 100644
--- a/drivers/staging/greybus/tools/loopback_test.c
+++ b/drivers/staging/greybus/tools/loopback_test.c
@@ -20,6 +20,7 @@
 #include <signal.h>
 
 #define MAX_NUM_DEVICES 10
+#define MAX_SYSFS_PREFIX 0x80
 #define MAX_SYSFS_PATH	0x200
 #define CSV_MAX_LINE	0x1000
 #define SYSFS_MAX_INT	0x20
@@ -68,7 +69,7 @@ struct loopback_results {
 };
 
 struct loopback_device {
-	char name[MAX_SYSFS_PATH];
+	char name[MAX_STR_LEN];
 	char sysfs_entry[MAX_SYSFS_PATH];
 	char debugfs_entry[MAX_SYSFS_PATH];
 	struct loopback_results results;
@@ -94,8 +95,8 @@ struct loopback_test {
 	int stop_all;
 	int poll_count;
 	char test_name[MAX_STR_LEN];
-	char sysfs_prefix[MAX_SYSFS_PATH];
-	char debugfs_prefix[MAX_SYSFS_PATH];
+	char sysfs_prefix[MAX_SYSFS_PREFIX];
+	char debugfs_prefix[MAX_SYSFS_PREFIX];
 	struct timespec poll_timeout;
 	struct loopback_device devices[MAX_NUM_DEVICES];
 	struct loopback_results aggregate_results;
@@ -917,10 +918,10 @@ int main(int argc, char *argv[])
 			t.iteration_max = atoi(optarg);
 			break;
 		case 'S':
-			snprintf(t.sysfs_prefix, MAX_SYSFS_PATH, "%s", optarg);
+			snprintf(t.sysfs_prefix, MAX_SYSFS_PREFIX, "%s", optarg);
 			break;
 		case 'D':
-			snprintf(t.debugfs_prefix, MAX_SYSFS_PATH, "%s", optarg);
+			snprintf(t.debugfs_prefix, MAX_SYSFS_PREFIX, "%s", optarg);
 			break;
 		case 'm':
 			t.mask = atol(optarg);
@@ -971,10 +972,10 @@ int main(int argc, char *argv[])
 	}
 
 	if (!strcmp(t.sysfs_prefix, ""))
-		snprintf(t.sysfs_prefix, MAX_SYSFS_PATH, "%s", sysfs_prefix);
+		snprintf(t.sysfs_prefix, MAX_SYSFS_PREFIX, "%s", sysfs_prefix);
 
 	if (!strcmp(t.debugfs_prefix, ""))
-		snprintf(t.debugfs_prefix, MAX_SYSFS_PATH, "%s", debugfs_prefix);
+		snprintf(t.debugfs_prefix, MAX_SYSFS_PREFIX, "%s", debugfs_prefix);
 
 	ret = find_loopback_devices(&t);
 	if (ret)
-- 
2.20.1

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