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Subject[PATCH 4.19 77/92] nfs: Fix getxattr kernel panic and memory overflow
Date
From: Jeffrey Mitchell <jeffrey.mitchell@starlab.io>

[ Upstream commit b4487b93545214a9db8cbf32e86411677b0cca21 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/nfs4proc.c | 2 --
fs/nfs/nfs4xdr.c | 6 +++++-
2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 05cb68ca1ba1a..1ef75b1deffa3 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5603,8 +5603,6 @@ static int _nfs4_get_security_label(struct inode *inode, void *buf,
return ret;
if (!(fattr.valid & NFS_ATTR_FATTR_V4_SECURITY_LABEL))
return -ENOENT;
- if (buflen < label.len)
- return -ERANGE;
return 0;
}

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index c4cf0192d7bb8..0a5cae8f8aff9 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4280,7 +4280,11 @@ static int decode_attr_security_label(struct xdr_stream *xdr, uint32_t *bitmap,
goto out_overflow;
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;
--
2.25.1


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