From: Chuck Lever chuck.lever@oracle.com
[ Upstream commit 1242a87da0d8cd2a428e96ca68e7ea899b0f4624 ]
Commit 2825a7f90753 ("nfsd4: allow encoding across page boundaries") added an explicit computation of the remaining length in the rq_res XDR buffer.
The computation appears to suffer from an "off-by-one" bug. Because buflen is too large by one page, XDR encoding can run off the end of the send buffer by eventually trying to use the struct page address in rq_page_end, which always contains NULL.
Fixes: bddfdbcddbe2 ("NFSD: Extract the svcxdr_init_encode() helper") Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/sunrpc/svc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 6be55d0e73fd..045f34add206 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -609,7 +609,7 @@ static inline void svcxdr_init_encode(struct svc_rqst *rqstp) xdr->end = resv->iov_base + PAGE_SIZE - rqstp->rq_auth_slack; buf->len = resv->iov_len; xdr->page_ptr = buf->pages - 1; - buf->buflen = PAGE_SIZE * (1 + rqstp->rq_page_end - buf->pages); + buf->buflen = PAGE_SIZE * (rqstp->rq_page_end - buf->pages); buf->buflen -= rqstp->rq_auth_slack; xdr->rqst = NULL; }