2022-03-24 20:55:18

by baihaowen

Subject: [PATCH] SUNRPC: Increase size of servername string

This patch will fix the warning from smatch:

net/sunrpc/clnt.c:562 rpc_create() error: snprintf() chops off
the last chars of 'sun->sun_path': 108 vs 48

Signed-off-by: Haowen Bai <[email protected]>
---
net/sunrpc/clnt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index c83fe61..6e0209e 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -526,7 +526,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
.servername = args->servername,
.bc_xprt = args->bc_xprt,
};
- char servername[48];
+ char servername[108];
struct rpc_clnt *clnt;
int i;

--
2.7.4

2022-03-25 11:34:52

by David Laight

Subject: RE: [PATCH] SUNRPC: Increase size of servername string

From: NeilBrown
> Sent: 25 March 2022 02:07
>
> On Thu, 24 Mar 2022, Haowen Bai wrote:
> > This patch will fix the warning from smatch:
> >
> > net/sunrpc/clnt.c:562 rpc_create() error: snprintf() chops off
> > the last chars of 'sun->sun_path': 108 vs 48
> >
> > Signed-off-by: Haowen Bai <[email protected]>
> > ---
> > net/sunrpc/clnt.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> > index c83fe61..6e0209e 100644
> > --- a/net/sunrpc/clnt.c
> > +++ b/net/sunrpc/clnt.c
> > @@ -526,7 +526,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
> > .servername = args->servername,
> > .bc_xprt = args->bc_xprt,
> > };
> > - char servername[48];
> > + char servername[108];
>
> It would be much nicer to use UNIX_PATH_MAX

No on-stack....

Given the use:

if (xprtargs.servername == NULL) {
struct sockaddr_un *sun =
(struct sockaddr_un *)args->address;
struct sockaddr_in *sin =
(struct sockaddr_in *)args->address;
struct sockaddr_in6 *sin6 =
(struct sockaddr_in6 *)args->address;

servername[0] = '\0';
switch (args->address->sa_family) {
case AF_LOCAL:
snprintf(servername, sizeof(servername), "%s",
sun->sun_path);
break;
case AF_INET:
snprintf(servername, sizeof(servername), "%pI4",
&sin->sin_addr.s_addr);
break;
case AF_INET6:
snprintf(servername, sizeof(servername), "%pI6",
&sin6->sin6_addr);
break;
default:
/* caller wants default server name, but
* address family isn't recognized. */
return ERR_PTR(-EINVAL);
}
xprtargs.servername = servername;
}

It looks like the AF_LOCAL case could be:
xprtargs.servername = sun->sun_path;
Then the buffer only needs to be big enough for the IPv6 address.
For which 40 is enough.

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

2022-03-25 18:07:28

by NeilBrown

Subject: Re: [PATCH] SUNRPC: Increase size of servername string

On Thu, 24 Mar 2022, Haowen Bai wrote:
> This patch will fix the warning from smatch:
>
> net/sunrpc/clnt.c:562 rpc_create() error: snprintf() chops off
> the last chars of 'sun->sun_path': 108 vs 48
>
> Signed-off-by: Haowen Bai <[email protected]>
> ---
> net/sunrpc/clnt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index c83fe61..6e0209e 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -526,7 +526,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
> .servername = args->servername,
> .bc_xprt = args->bc_xprt,
> };
> - char servername[48];
> + char servername[108];

It would be much nicer to use UNIX_PATH_MAX

NeilBrown


> struct rpc_clnt *clnt;
> int i;
>
> --
> 2.7.4
>
>