[PATCH 3/3] i2ctransfer: Zero out memory passed to ioctl()

[Jean Delvare <jdelvare@suse.de>]

Valgrind complains that uninitialized memory may be passed to
ioctl():

== Syscall param ioctl(I2C_RDWR) points to uninitialised byte(s)
==    at 0x499382B: ioctl (in /lib64/libc.so.6)
==    by 0x401957: main (i2ctransfer.c:343)
==  Address 0x1ffefff94c is on thread 1's stack
==  in frame #1, created by main (i2ctransfer.c:144)
== 
== Syscall param ioctl(I2C_RDWR).msgs points to uninitialised byte(s)
==    at 0x499382B: ioctl (in /lib64/libc.so.6)
==    by 0x401957: main (i2ctransfer.c:343)
==  Address 0x1ffefff956 is on thread 1's stack
==  in frame #1, created by main (i2ctransfer.c:144)

Zero out the i2c_rdwr_ioctl_data struct as well as the msgs array to
guarantee that no uninitialized memory will ever be passed to the
kernel.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
This one is not strictly needed, I can't see any actual bug. However
making valgrind happy seems to be a sane goal, so that we can keep
using it when debugging other issues without getting distracted.
Wolfram, what do you think?

 tools/i2ctransfer.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- i2c-tools.orig/tools/i2ctransfer.c
+++ i2c-tools/tools/i2ctransfer.c
@@ -149,8 +149,7 @@ int main(int argc, char *argv[])
 	enum parse_state state = PARSE_GET_DESC;
 	unsigned int buf_idx = 0;
 
-	for (i = 0; i < I2C_RDRW_IOCTL_MAX_MSGS; i++)
-		msgs[i].buf = NULL;
+	memset(msgs, 0, sizeof(msgs));
 
 	/* handle (optional) flags first */
 	while ((opt = getopt(argc, argv, "abfhvVy")) != -1) {
@@ -334,6 +333,7 @@ int main(int argc, char *argv[])
 		struct i2c_rdwr_ioctl_data rdwr;
 		unsigned int print_flags = PRINT_READ_BUF;
 
+		memset(&rdwr, 0, sizeof(rdwr));
 		rdwr.msgs = msgs;
 		rdwr.nmsgs = nmsgs;
 		nmsgs_sent = ioctl(file, I2C_RDWR, &rdwr);

-- 
Jean Delvare
SUSE L3 Support