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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>,
	Anna Schumaker <Anna.Schumaker@Netapp.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-nfs@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 03/43] fs: nfs: Fix possible null-pointer dereferences in encode_attrs()
Date: Tue,  1 Oct 2019 12:42:31 -0400
Message-ID: <20191001164311.15993-3-sashal@kernel.org> (raw)
In-Reply-To: <20191001164311.15993-1-sashal@kernel.org>

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit e2751463eaa6f9fec8fea80abbdc62dbc487b3c5 ]

In encode_attrs(), there is an if statement on line 1145 to check
whether label is NULL:
    if (label && (attrmask[2] & FATTR4_WORD2_SECURITY_LABEL))

When label is NULL, it is used on lines 1178-1181:
    *p++ = cpu_to_be32(label->lfs);
    *p++ = cpu_to_be32(label->pi);
    *p++ = cpu_to_be32(label->len);
    p = xdr_encode_opaque_fixed(p, label->label, label->len);

To fix these bugs, label is checked before being used.

These bugs are found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfs/nfs4xdr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index b7bde12d8cd51..1c0227c78a7bc 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1171,7 +1171,7 @@ static void encode_attrs(struct xdr_stream *xdr, const struct iattr *iap,
 		} else
 			*p++ = cpu_to_be32(NFS4_SET_TO_SERVER_TIME);
 	}
-	if (bmval[2] & FATTR4_WORD2_SECURITY_LABEL) {
+	if (label && (bmval[2] & FATTR4_WORD2_SECURITY_LABEL)) {
 		*p++ = cpu_to_be32(label->lfs);
 		*p++ = cpu_to_be32(label->pi);
 		*p++ = cpu_to_be32(label->len);
-- 
2.20.1


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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191001164311.15993-1-sashal@kernel.org>
2019-10-01 16:42 ` Sasha Levin [this message]
2019-10-01 16:42 ` [PATCH AUTOSEL 4.19 15/43] pNFS: Ensure we do clear the return-on-close layout stateid on fatal errors Sasha Levin

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