From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5FC73BB675 for ; Thu, 23 Jul 2026 18:19:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784830772; cv=none; b=d2QIm6ONJbvdyMQ6jIcw5q2j4vxLCXjxSmSdAsRlnhfJ+xySQtTe7FbBxl2cAgKwvwog5SgVWgv0ZqZUyoc8PV8bH+OwO0tKIorPx5x90JbWKDOVHwXQF4af30v5Ck+VyL0B2V//MJj1fLyVaE1DvBuDObFiLcH3gj2L3j8a1Zw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784830772; c=relaxed/simple; bh=6ea/zhRse0NfEggJJQKqp0MhVOesaxV63j6BHefNsRc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bz+7iv1xlbe3TxHJTMgK7jAPSXaL0pB93cqxHxwQZczkorP0F+JCusPk19TAgbzJISKI6JOc0k199BgLAY4mqsJFlNTInZ2tWcBIUOdk6Wkc+wB5oFkgOFD58pdGg9XCjeSNZMmF5t56gmnzgQOwz9iWrY/VgznVuQAG7/dzAIA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01D0F1F00AC4; Thu, 23 Jul 2026 18:19:16 +0000 (UTC) From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Chris Mason , Jeff Layton , Sasha Levin Subject: [PATCH 6.18.y 5/5] SUNRPC: Return an error from xdr_buf_to_bvec() on overflow Date: Thu, 23 Jul 2026 14:19:10 -0400 Message-ID: <20260723181911.3438372-5-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260723181911.3438372-1-sashal@kernel.org> References: <2026072057-lapped-rebate-93bd@gregkh> <20260723181911.3438372-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 18c1cc69886192e33536498289d26dba6894e3d5 ] xdr_buf_to_bvec() returns a slot count even when the caller's bvec budget is exhausted partway through the xdr_buf. Callers feed that count into iov_iter_bvec() and continue as if the conversion had succeeded, silently sending or writing fewer bytes than the data length declares. For an NFS WRITE the server reports the truncated transfer to the client as full success. The overflow represents an internal invariant violation: a higher layer reserved a bvec budget too small for the xdr_buf it then asked the encoder to convert. That is a server-side fault, not a media I/O failure and not a malformed client argument. Change xdr_buf_to_bvec() to return a signed int and have the overflow label return -ESERVERFAULT. Update the three callers to detect the negative return and fail the request: nfsd_vfs_write() folds the error into host_err, which nfserrno() translates to nfserr_serverfault for the WRITE reply; svc_udp_sendto() and svc_tcp_sendmsg() propagate the error out of the send path. Reported-by: Chris Mason Fixes: 2eb2b9358181 ("SUNRPC: Convert svc_tcp_sendmsg to use bio_vecs directly") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/vfs.c | 8 +++++++- include/linux/sunrpc/xdr.h | 4 ++-- net/sunrpc/svcsock.c | 14 ++++++++++++-- net/sunrpc/xdr.c | 11 ++++++----- 4 files changed, 27 insertions(+), 10 deletions(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 4874446c2468d8..ba882a4ea9cb9d 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1203,7 +1203,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned long exp_op_flags = 0; unsigned int pflags = current->flags; bool restore_flags = false; - unsigned int nvecs; + int nvecs; trace_nfsd_write_opened(rqstp, fhp, offset, *cnt); @@ -1243,7 +1243,13 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, } nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload); + if (nvecs < 0) { + host_err = nvecs; + goto out_nfserr; + } + iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); + since = READ_ONCE(file->f_wb_err); if (verf) nfsd_copy_write_verifier(verf, nn); diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h index 4b4e767e2ab5bd..656e0ad323af1b 100644 --- a/include/linux/sunrpc/xdr.h +++ b/include/linux/sunrpc/xdr.h @@ -138,8 +138,8 @@ void xdr_terminate_string(const struct xdr_buf *, const u32); size_t xdr_buf_pagecount(const struct xdr_buf *buf); int xdr_alloc_bvec(struct xdr_buf *buf, gfp_t gfp); void xdr_free_bvec(struct xdr_buf *buf); -unsigned int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size, - const struct xdr_buf *xdr); +int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size, + const struct xdr_buf *xdr); int xdr_buf_to_sg(const struct xdr_buf *buf, unsigned int offset, unsigned int len, struct scatterlist *sg, unsigned int nsg); int xdr_buf_to_sg_alloc(const struct xdr_buf *buf, unsigned int offset, diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c index 48700b99909fac..038294fa3942a5 100644 --- a/net/sunrpc/svcsock.c +++ b/net/sunrpc/svcsock.c @@ -738,7 +738,7 @@ static int svc_udp_sendto(struct svc_rqst *rqstp) .msg_flags = MSG_SPLICE_PAGES, .msg_controllen = sizeof(buffer), }; - unsigned int count; + int count; int err; svc_udp_release_ctxt(xprt, rqstp->rq_xprt_ctxt); @@ -752,6 +752,10 @@ static int svc_udp_sendto(struct svc_rqst *rqstp) goto out_notconn; count = xdr_buf_to_bvec(svsk->sk_bvec, SUNRPC_MAX_UDP_SENDPAGES, xdr); + if (count < 0) { + err = count; + goto out_trace; + } iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, svsk->sk_bvec, count, rqstp->rq_res.len); @@ -763,6 +767,7 @@ static int svc_udp_sendto(struct svc_rqst *rqstp) err = sock_sendmsg(svsk->sk_sock, &msg); } +out_trace: trace_svcsock_udp_send(xprt, err); mutex_unlock(&xprt->xpt_mutex); @@ -1241,7 +1246,7 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp, struct msghdr msg = { .msg_flags = MSG_SPLICE_PAGES, }; - unsigned int count; + int count; void *buf; int ret; @@ -1257,10 +1262,15 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp, count = xdr_buf_to_bvec(svsk->sk_bvec + 1, rqstp->rq_maxpages, &rqstp->rq_res); + if (count < 0) { + ret = count; + goto out; + } iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, svsk->sk_bvec, 1 + count, sizeof(marker) + rqstp->rq_res.len); ret = sock_sendmsg(svsk->sk_sock, &msg); +out: page_frag_free(buf); return ret; } diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 82d3e8f65e486a..fb4dab2070007f 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -139,13 +139,14 @@ xdr_free_bvec(struct xdr_buf *buf) /** * xdr_buf_to_bvec - Copy components of an xdr_buf into a bio_vec array * @bvec: bio_vec array to populate - * @bvec_size: element count of @bio_vec + * @bvec_size: element count of @bvec * @xdr: xdr_buf to be copied * - * Returns the number of entries consumed in @bvec. + * Returns the number of entries consumed in @bvec on success, or + * -ESERVERFAULT when @xdr does not fit within @bvec_size entries. */ -unsigned int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size, - const struct xdr_buf *xdr) +int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size, + const struct xdr_buf *xdr) { const struct kvec *head = xdr->head; const struct kvec *tail = xdr->tail; @@ -187,7 +188,7 @@ unsigned int xdr_buf_to_bvec(struct bio_vec *bvec, unsigned int bvec_size, bvec_overflow: pr_warn_once("%s: bio_vec array overflow\n", __func__); - return count; + return -ESERVERFAULT; } EXPORT_SYMBOL_GPL(xdr_buf_to_bvec); -- 2.53.0