[1/1] nfsd: enforce upper limit for namelen in __cld_pipe_inprogress_downcall()

Commit Message

Scott Mayhew Sept. 9, 2024, 8:28 p.m. UTC

This patch is intended to go on top of "nfsd: return -EINVAL when
namelen is 0" from Li Lingfeng.  Li's patch checks for 0, but we should
be enforcing an upper bound as well.

Note that if nfsdcld somehow gets an id > NFS4_OPAQUE_LIMIT in its
database, it'll truncate it to NFS4_OPAQUE_LIMIT when it does the
downcall anyway.

Signed-off-by: Scott Mayhew <[e-mail]>
---
 fs/nfsd/nfs4recover.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 69a3a84e159e..a2b995ee77f4 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -809,8 +809,8 @@  __cld_pipe_inprogress_downcall(const struct cld_msg_v2 __user *cmsg,
 			ci = &cmsg->cm_u.cm_clntinfo;
 			if (get_user(namelen, &ci->cc_name.cn_len))
 				return -EFAULT;
-			if (!namelen) {
-				dprintk("%s: namelen should not be zero", __func__);
+			if (namelen == 0 || namelen > NFS4_OPAQUE_LIMIT) {
+				dprintk("%s: invalid namelen (%u)", __func__, namelen);
 				return -EINVAL;
 			}
 			name.data = memdup_user(&ci->cc_name.cn_id, namelen);
@@ -835,8 +835,8 @@  __cld_pipe_inprogress_downcall(const struct cld_msg_v2 __user *cmsg,
 			cnm = &cmsg->cm_u.cm_name;
 			if (get_user(namelen, &cnm->cn_len))
 				return -EFAULT;
-			if (!namelen) {
-				dprintk("%s: namelen should not be zero", __func__);
+			if (namelen == 0 || namelen > NFS4_OPAQUE_LIMIT) {
+				dprintk("%s: invalid namelen (%u)", __func__, namelen);
 				return -EINVAL;
 			}
 			name.data = memdup_user(&cnm->cn_id, namelen);