From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
Normally xdr encoding proceeds in a single pass from start of a buffer
to end, but sometimes we have to write a few bytes to an earlier
position.
Use write_bytes_to_xdr_buf for these cases rather than saving a pointer
to write to. We plan to rewrite xdr_reserve_space to handle encoding
across page boundaries using a scratch buffer, and don't want to risk
writing to a pointer that was contained in a scratch buffer.
Also it will no longer be safe to calculate lengths by subtracting two
pointers, so use xdr_buf offsets instead.
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
---
fs/nfsd/nfs4xdr.c | 44 ++++++++++++++++++++++++++------------------
1 file changed, 26 insertions(+), 18 deletions(-)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index da6b43d..cc219b8 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1757,16 +1757,19 @@ static void write_cinfo(__be32 **p, struct nfsd4_change_info *c)
static __be32 nfsd4_encode_components_esc(struct xdr_stream *xdr, char sep, char *components, char esc_enter, char esc_exit)
{
__be32 *p;
- __be32 *countp;
+ __be32 pathlen;
+ int pathlen_offset;
int strlen, count=0;
char *str, *end, *next;
dprintk("nfsd4_encode_components(%s)\n", components);
+
+ pathlen_offset = xdr->buf->len;
p = xdr_reserve_space(xdr, 4);
if (!p)
return nfserr_resource;
- countp = p;
- WRITE32(0); /* We will fill this in with @count later */
+ p++; /* We will fill this in with @count later */
+
end = str = components;
while (*end) {
bool found_esc = false;
@@ -1799,8 +1802,8 @@ static __be32 nfsd4_encode_components_esc(struct xdr_stream *xdr, char sep, char
end++;
str = end;
}
- p = countp;
- WRITE32(count);
+ pathlen = htonl(xdr->buf->len - pathlen_offset);
+ write_bytes_to_xdr_buf(xdr->buf, pathlen_offset, &pathlen, 4);
return 0;
}
@@ -2042,7 +2045,8 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp, struct svc_export
struct kstatfs statfs;
__be32 *p;
int starting_len = xdr->buf->len;
- __be32 *attrlenp;
+ int attrlen_offset;
+ __be32 attrlen;
u32 dummy;
u64 dummy64;
u32 rdattr_err = 0;
@@ -2147,10 +2151,12 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp, struct svc_export
WRITE32(1);
WRITE32(bmval0);
}
+
+ attrlen_offset = xdr->buf->len;
p = xdr_reserve_space(xdr, 4);
if (!p)
goto out_resource;
- attrlenp = p++; /* to be backfilled later */
+ p++; /* to be backfilled later */
if (bmval0 & FATTR4_WORD0_SUPPORTED_ATTRS) {
u32 word0 = nfsd_suppattrs0(minorversion);
@@ -2521,7 +2527,8 @@ out_acl:
WRITE32(NFSD_SUPPATTR_EXCLCREAT_WORD2);
}
- *attrlenp = htonl((char *)xdr->p - (char *)attrlenp - 4);
+ attrlen = htonl(xdr->buf->len - attrlen_offset - 4);
+ write_bytes_to_xdr_buf(xdr->buf, attrlen_offset, &attrlen, 4);
status = nfs_ok;
out:
@@ -3648,15 +3655,16 @@ __be32 nfsd4_check_resp_size(struct nfsd4_compoundres *resp, u32 pad)
void
nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
{
+ struct xdr_stream *xdr = &resp->xdr;
struct nfs4_stateowner *so = resp->cstate.replay_owner;
struct svc_rqst *rqstp = resp->rqstp;
- __be32 *statp;
+ int post_err_offset;
nfsd4_enc encoder;
__be32 *p;
RESERVE_SPACE(8);
WRITE32(op->opnum);
- statp = p++; /* to be backfilled at the end */
+ post_err_offset = xdr->buf->len;
if (op->opnum == OP_ILLEGAL)
goto status;
@@ -3687,19 +3695,19 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
nfsd4_op_name(op->opnum));
WARN_ON_ONCE(1);
}
- resp->xdr.p = statp + 1;
+ xdr_truncate_encode(xdr, post_err_offset);
}
if (so) {
+ int len = xdr->buf->len - post_err_offset;
+
so->so_replay.rp_status = op->status;
- so->so_replay.rp_buflen = (char *)resp->xdr.p - (char *)(statp+1);
- memcpy(so->so_replay.rp_buf, statp+1, so->so_replay.rp_buflen);
+ so->so_replay.rp_buflen = len;
+ read_bytes_from_xdr_buf(xdr->buf, post_err_offset,
+ so->so_replay.rp_buf, len);
}
status:
- /*
- * Note: We write the status directly, instead of using WRITE32(),
- * since it is already in network byte order.
- */
- *statp = op->status;
+ /* Note that op->status is already in network byte order: */
+ write_bytes_to_xdr_buf(xdr->buf, post_err_offset - 4, &op->status, 4);
}
/*
--
1.7.9.5
--
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