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[v2,3/4] NFSv4.2: Fix a memory stomp in decode_attr_security_label

Message ID 20221019173651.32096-3-trondmy@kernel.org (mailing list archive)
State New, archived
Headers show
Series [v2,1/4] NFSv4.2: Clear FATTR4_WORD2_SECURITY_LABEL when done decoding | expand

Commit Message

Trond Myklebust Oct. 19, 2022, 5:36 p.m. UTC 
From: Trond Myklebust <trond.myklebust@hammerspace.com>

We must not change the value of label->len if it is zero, since that
indicates we stored a label.

Fixes: b4487b935452 ("nfs: Fix getxattr kernel panic and memory overflow")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/nfs4xdr.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)
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Patch

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 9103e022376a..deec76cf5afe 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4236,12 +4236,10 @@  static int decode_attr_security_label(struct xdr_stream *xdr, uint32_t *bitmap,
 			return -EIO;
 		bitmap[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
 		if (len < NFS4_MAXLABELLEN) {
-			if (label) {
-				if (label->len) {
-					if (label->len < len)
-						return -ERANGE;
-					memcpy(label->label, p, len);
-				}
+			if (label && label->len) {
+				if (label->len < len)
+					return -ERANGE;
+				memcpy(label->label, p, len);
 				label->len = len;
 				label->pi = pi;
 				label->lfs = lfs;