Re: [PATCH] net/sunrpc: Fix return value from proc_do_xprt()

Alex Dewar
2020-11-07T13:50:33Z

On Fri, Nov 06, 2020 at 05:07:21PM -0500, J. Bruce Fields wrote:
> Whoops, got 3 independent patches for this and overlooked this one. See
> https://lore.kernel.org/linux-nfs/20201106205959.GB26028@fieldses.org/T/#t
>
> --b.

That looks like a cleaner fix. Thanks for looking anyhow and sorry for
the noise!

>
> On Sat, Oct 24, 2020 at 03:52:40PM +0100, Alex Dewar wrote:
> > Commit c09f56b8f68d ("net/sunrpc: Fix return value for sysctl
> > sunrpc.transports") attempted to add error checking for the call to
> > memory_read_from_buffer(), however its return value was assigned to a
> > size_t variable, so any negative values would be lost in the cast. Fix
> > this.
> >
> > Addresses-Coverity-ID: 1498033: Control flow issues (NO_EFFECT)
> > Fixes: c09f56b8f68d ("net/sunrpc: Fix return value for sysctl sunrpc.transports")
> > Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
> > ---
> > net/sunrpc/sysctl.c | 7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
> > index a18b36b5422d..c95a2b84dd95 100644
> > --- a/net/sunrpc/sysctl.c
> > +++ b/net/sunrpc/sysctl.c
> > @@ -62,6 +62,7 @@ rpc_unregister_sysctl(void)
> > static int proc_do_xprt(struct ctl_table *table, int write,
> > void *buffer, size_t *lenp, loff_t *ppos)
> > {
> > + ssize_t bytes_read;
> > char tmpbuf[256];
> > size_t len;
> >
> > @@ -70,12 +71,14 @@ static int proc_do_xprt(struct ctl_table *table, int write,
> > return 0;
> > }
> > len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
> > - *lenp = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
> > + bytes_read = memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
> >
> > - if (*lenp < 0) {
> > + if (bytes_read < 0) {
> > *lenp = 0;
> > return -EINVAL;
> > }
> > +
> > + *lenp = bytes_read;
> > return 0;
> > }
> >
> > --
> > 2.29.1