[PATCH] cifs: remove misleading strncpy: each name has length < 16

[Bastien ROUCARIES]

Le 20 août 2012 19:29, "Jim Meyering" <jim at meyering.net> a écrit :
>
> From: Jim Meyering <meyering at redhat.com>
>
> Each of the protocols[i].name strings (statically declared above)
> has length less than 16, so this use of strncpy is misleading:
>   strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
> Besides, if a new name were added with length N >= 16, the existing
> strncpy-using code would be buggy, creating a ->DialectsArray buffer
> containing N-16+1 unset bytes where the NUL terminator should have
> been.  Instead, traverse the name only once go get its length,
> use a BUG_ON assertion to enforce the length restriction
> and use memcpy to perform the copy.
>

Could you use ARRAY_SIZE instead of hard coding 16?
> Signed-off-by: Jim Meyering <meyering at redhat.com>
> ---
>  fs/cifs/cifssmb.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index 074923c..16a9018 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -441,8 +441,10 @@ CIFSSMBNegotiate(const unsigned int xid, struct
cifs_ses *ses)
>
>         count = 0;
>         for (i = 0; i < CIFS_NUM_PROT; i++) {
> -               strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
> -               count += strlen(protocols[i].name) + 1;
> +               size_t len = strlen(protocols[i].name);
> +               BUG_ON(len >= 16);
> +               memcpy(pSMB->DialectsArray+count, protocols[i].name, len
+ 1);
> +               count += len + 1;
>                 /* null at end of source and target buffers anyway */
>         }
>         inc_rfc1001_len(pSMB, count);
> --
> 1.7.12
>
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