This is a note to let you know that I've just added the patch titled NFSv4.2: Fix a memory stomp in decode_attr_security_label to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nfsv4.2-fix-a-memory-stomp-in-decode_attr_security_l.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 4666cc26ad18b7e4ee17cf728389fa2e7eb51cfd Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Date: Tue Oct 18 18:21:14 2022 -0400 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 <trond.myklebust@xxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c index ac9ffe184451..a3592becae4a 100644 --- a/fs/nfs/nfs4xdr.c +++ b/fs/nfs/nfs4xdr.c @@ -4171,12 +4171,10 @@ 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;