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net: dsa: remove deprecated strncpy

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`strncpy` is deprecated for use on NUL-terminated destination strings [1].

Even call sites utilizing length-bounded destination buffers should
switch over to using `strtomem` or `strtomem_pad`. In this case,
however, the compiler is unable to determine the size of the `data`
buffer which renders `strtomem` unusable. Due to this, `strscpy`
should be used.

It should be noted that most call sites already zero-initialize the
destination buffer. However, I've opted to use `strscpy_pad` to maintain
the same exact behavior that `strncpy` produced (zero-padded tail up to
`len`).

Also see [3].

[1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
[2]: elixir.bootlin.com/linux/v6.3/source/net/ethtool/ioctl.c#L1944
[3]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html

Link: https://github.com/KSPP/linux/issues/90
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
justinstitt@google.com 2023-07-18 22:56:38 +00:00 committed by David S. Miller
parent 2e60314c28
commit 5c9f7b04aa
1 changed files with 5 additions and 4 deletions
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9
net/dsa/slave.c
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@ -21,6 +21,7 @@
#include <linux/if_hsr.h>
#include <net/dcbnl.h>
#include <linux/netpoll.h>
#include <linux/string.h>
#include "dsa.h"
#include "port.h"
@ -1056,10 +1057,10 @@ static void dsa_slave_get_strings(struct net_device *dev,
if (stringset == ETH_SS_STATS) {
int len = ETH_GSTRING_LEN;
strncpy(data, "tx_packets", len);
strncpy(data + len, "tx_bytes", len);
strncpy(data + 2 * len, "rx_packets", len);
strncpy(data + 3 * len, "rx_bytes", len);
strscpy_pad(data, "tx_packets", len);
strscpy_pad(data + len, "tx_bytes", len);
strscpy_pad(data + 2 * len, "rx_packets", len);
strscpy_pad(data + 3 * len, "rx_bytes", len);
if (ds->ops->get_strings)
ds->ops->get_strings(ds, dp->index, stringset,
data + 4 * len);