RE: [PATCH] ar5523: check NULL before memcpy() in ar5523_cmd()

David Laight
2019-09-30T15:35:47Z

From: Denis Efremov
> Sent: 30 September 2019 15:02
>
> memcpy() call with "idata == NULL && ilen == 0" results in undefined
> behavior in ar5523_cmd(). For example, NULL is passed in callchain
> "ar5523_stat_work() -> ar5523_cmd_write() -> ar5523_cmd()". This patch
> adds idata check before memcpy() call in ar5523_cmd() to prevent an
> undefined behavior.
>
...
> Signed-off-by: Denis Efremov <efremov@linux.com>
> ---
> drivers/net/wireless/ath/ar5523/ar5523.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
> index b94759daeacc..f25af5bc5282 100644
> --- a/drivers/net/wireless/ath/ar5523/ar5523.c
> +++ b/drivers/net/wireless/ath/ar5523/ar5523.c
> @@ -255,7 +255,8 @@ static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,
>
> if (flags & AR5523_CMD_FLAG_MAGIC)
> hdr->magic = cpu_to_be32(1 << 24);
> - memcpy(hdr + 1, idata, ilen);
> + if (idata)
> + memcpy(hdr + 1, idata, ilen);

That would be better as if (ilen) ...

David

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