linux-kernel - [PATCH 5.10 14/83] nfsd4: Handle the NFSv4 READDIR dircount hint being zero

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211011134508.846916958@linuxfoundation.org>
Date:   Mon, 11 Oct 2021 15:45:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Chuck Lever <chuck.lever@...cle.com>
Subject: [PATCH 5.10 14/83] nfsd4: Handle the NFSv4 READDIR dircount hint being zero

From: Trond Myklebust <trond.myklebust@...merspace.com>

commit f2e717d655040d632c9015f19aa4275f8b16e7f2 upstream.

RFC3530 notes that the 'dircount' field may be zero, in which case the
recommendation is to ignore it, and only enforce the 'maxcount' field.
In RFC5661, this recommendation to ignore a zero valued field becomes a
requirement.

Fixes: aee377644146 ("nfsd4: fix rd_dircount enforcement")
Cc: <stable@...r.kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@...merspace.com>
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/nfsd/nfs4xdr.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3427,15 +3427,18 @@ nfsd4_encode_dirent(void *ccdv, const ch
 		goto fail;
 	cd->rd_maxcount -= entry_bytes;
 	/*
-	 * RFC 3530 14.2.24 describes rd_dircount as only a "hint", so
-	 * let's always let through the first entry, at least:
+	 * RFC 3530 14.2.24 describes rd_dircount as only a "hint", and
+	 * notes that it could be zero. If it is zero, then the server
+	 * should enforce only the rd_maxcount value.
 	 */
-	if (!cd->rd_dircount)
-		goto fail;
-	name_and_cookie = 4 + 4 * XDR_QUADLEN(namlen) + 8;
-	if (name_and_cookie > cd->rd_dircount && cd->cookie_offset)
-		goto fail;
-	cd->rd_dircount -= min(cd->rd_dircount, name_and_cookie);
+	if (cd->rd_dircount) {
+		name_and_cookie = 4 + 4 * XDR_QUADLEN(namlen) + 8;
+		if (name_and_cookie > cd->rd_dircount && cd->cookie_offset)
+			goto fail;
+		cd->rd_dircount -= min(cd->rd_dircount, name_and_cookie);
+		if (!cd->rd_dircount)
+			cd->rd_maxcount = 0;
+	}
 
 	cd->cookie_offset = cookie_offset;
 skip_entry: