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authorTrond Myklebust <trond.myklebust@hammerspace.com>2021-09-30 15:44:41 -0400
committerChuck Lever <chuck.lever@oracle.com>2021-09-30 16:53:17 -0400
commitf2e717d655040d632c9015f19aa4275f8b16e7f2 (patch)
treee94de61245fb6108c742ca1ba6fca97e81605c41 /fs/nfsd
parent1d625050c7c2dd877e108e382b8aaf1ae3cfe1f4 (diff)
nfsd4: Handle the NFSv4 READDIR 'dircount' hint being zero
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@vger.kernel.org> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/nfs4xdr.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 7abeccb975b2..cf030ebe2827 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3544,15 +3544,18 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen,
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;
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