From: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>
Date: Wed, 5 Aug 2020 12:23:19 -0500
Subject: [PATCH] nfs: Fix getxattr kernel panic and memory overflow
Git-commit: b4487b93545214a9db8cbf32e86411677b0cca21
Patch-mainline: v5.9-rc1
References: bsc#1176381 CVE-2020-25212
Move the buffer size check to decode_attr_security_label() before memcpy()
Only call memcpy() if the buffer is large enough
Fixes: aa9c2669626c ("NFS: Client implementation of Labeled-NFS")
Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>
[trond: clean up duplicate test of label->len != 0]
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>
---
fs/nfs/nfs4proc.c | 2 --
fs/nfs/nfs4xdr.c | 6 +++++-
2 files changed, 5 insertions(+), 3 deletions(-)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5744,8 +5744,6 @@ static int _nfs4_get_security_label(stru
return ret;
if (!(fattr.valid & NFS_ATTR_FATTR_V4_SECURITY_LABEL))
return -ENOENT;
- if (buflen < label.len)
- return -ERANGE;
return 0;
}
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4169,7 +4169,11 @@ static int decode_attr_security_label(st
return -EIO;
if (len < NFS4_MAXLABELLEN) {
if (label) {
- memcpy(label->label, p, len);
+ if (label->len) {
+ if (label->len < len)
+ return -ERANGE;
+ memcpy(label->label, p, len);
+ }
label->len = len;
label->pi = pi;
label->lfs = lfs;