On Tue, Apr 25 2017, J. Bruce Fields wrote:
>> > + if (!*(rqstp->rq_next_page))
>> > + return 0;
>>
>> Why the extra parentheses? "->" is at the highest precedence level for C.
>
> I've been doing this stuff enough years, you'd think I'd have bothered
> to memorize the C operator precedence table by now.
>
> Anyway, this change is actually unrelated and not entirely necessary;
> dropped.
>
>> i.e. either keep it simple (like the v2 code) or make it tidy (with head
>> and tail), but not half-and-half??
>
> What the heck, let's go all out.
Looks good, thanks.
>
> You only live once!
:-)
NeilBrown
>
> --b.
>
> commit db44bac41bbf
> Author: J. Bruce Fields <bfields@xxxxxxxxxx>
> Date: Tue Apr 25 16:21:34 2017 -0400
>
> nfsd4: minor NFSv2/v3 write decoding cleanup
>
> Use a couple shortcuts that will simplify a following bugfix.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> index dba2ff8eaa68..d18cfddbe115 100644
> --- a/fs/nfsd/nfs3xdr.c
> +++ b/fs/nfsd/nfs3xdr.c
> @@ -358,6 +358,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> {
> unsigned int len, v, hdr, dlen;
> u32 max_blocksize = svc_max_payload(rqstp);
> + struct kvec *head = rqstp->rq_arg.head;
> + struct kvec *tail = rqstp->rq_arg.tail;
>
> p = decode_fh(p, &args->fh);
> if (!p)
> @@ -377,9 +379,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> * Check to make sure that we got the right number of
> * bytes.
> */
> - hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
> - dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
> - + rqstp->rq_arg.tail[0].iov_len - hdr;
> + hdr = (void*)p - head->iov_base;
> + dlen = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len - hdr;
> /*
> * Round the length of the data which was specified up to
> * the next multiple of XDR units and then compare that
> @@ -396,7 +397,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> len = args->len = max_blocksize;
> }
> rqstp->rq_vec[0].iov_base = (void*)p;
> - rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
> + rqstp->rq_vec[0].iov_len = head->iov_len - hdr;
> v = 0;
> while (len > rqstp->rq_vec[v].iov_len) {
> len -= rqstp->rq_vec[v].iov_len;
> diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
> index 41b468a6a90f..59bd88a23a3d 100644
> --- a/fs/nfsd/nfsxdr.c
> +++ b/fs/nfsd/nfsxdr.c
> @@ -280,6 +280,7 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> struct nfsd_writeargs *args)
> {
> unsigned int len, hdr, dlen;
> + struct kvec *head = rqstp->rq_arg.head;
> int v;
>
> p = decode_fh(p, &args->fh);
> @@ -300,9 +301,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> * Check to make sure that we got the right number of
> * bytes.
> */
> - hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
> - dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
> - - hdr;
> + hdr = (void*)p - head->iov_base;
> + dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
>
> /*
> * Round the length of the data which was specified up to
> @@ -316,7 +316,7 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> return 0;
>
> rqstp->rq_vec[0].iov_base = (void*)p;
> - rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
> + rqstp->rq_vec[0].iov_len = head->iov_len - hdr;
> v = 0;
> while (len > rqstp->rq_vec[v].iov_len) {
> len -= rqstp->rq_vec[v].iov_len;
> commit 13bf9fbff0e5
> Author: J. Bruce Fields <bfields@xxxxxxxxxx>
> Date: Fri Apr 21 15:26:30 2017 -0400
>
> nfsd: stricter decoding of write-like NFSv2/v3 ops
>
> The NFSv2/v3 code does not systematically check whether we decode past
> the end of the buffer. This generally appears to be harmless, but there
> are a few places where we do arithmetic on the pointers involved and
> don't account for the possibility that a length could be negative. Add
> checks to catch these.
>
> Reported-by: Tuomas Haanpää <thaan@xxxxxxxxxxxx>
> Reported-by: Ari Kauppi <ari@xxxxxxxxxxxx>
> Reviewed-by: NeilBrown <neilb@xxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> index d18cfddbe115..452334694a5d 100644
> --- a/fs/nfsd/nfs3xdr.c
> +++ b/fs/nfsd/nfs3xdr.c
> @@ -369,6 +369,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> args->count = ntohl(*p++);
> args->stable = ntohl(*p++);
> len = args->len = ntohl(*p++);
> + if ((void *)p > head->iov_base + head->iov_len)
> + return 0;
> /*
> * The count must equal the amount of data passed.
> */
> @@ -472,6 +474,8 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p,
> /* first copy and check from the first page */
> old = (char*)p;
> vec = &rqstp->rq_arg.head[0];
> + if ((void *)old > vec->iov_base + vec->iov_len)
> + return 0;
> avail = vec->iov_len - (old - (char*)vec->iov_base);
> while (len && avail && *old) {
> *new++ = *old++;
> diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
> index 59bd88a23a3d..de07ff625777 100644
> --- a/fs/nfsd/nfsxdr.c
> +++ b/fs/nfsd/nfsxdr.c
> @@ -302,6 +302,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
> * bytes.
> */
> hdr = (void*)p - head->iov_base;
> + if (hdr > head->iov_len)
> + return 0;
> dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
>
> /*
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Attachment:
signature.asc
Description: PGP signature
