From 51899eefd1a6c0e1b2fa8d4a0a93356252bfbe7f Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 18 Oct 2022 18:21:14 -0400 Subject: [PATCH] NFSv4.2: Fix a memory stomp in decode_attr_security_label [ Upstream commit 43c1031f7110967c240cb6e922adcfc4b8899183 ] 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 Signed-off-by: Sasha Levin --- fs/nfs/nfs4xdr.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c index 9d19b801..0ae9e06 100644 --- a/fs/nfs/nfs4xdr.c +++ b/fs/nfs/nfs4xdr.c @@ -4181,12 +4181,10 @@ 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; -- 2.7.4