[linux-yocto] [PATCH 3/4] nfsd: fix undefined behavior in nfsd4_layout_verify

[jianchuan.wang at windriver.com]

From: Ari Kauppi <ari at synopsys.com>

commit: b550a32e60a4941994b437a8d662432a486235a5 upstream

  UBSAN: Undefined behaviour in fs/nfsd/nfs4proc.c:1262:34
  shift exponent 128 is too large for 32-bit type 'int'

Depending on compiler+architecture, this may cause the check for
layout_type to succeed for overly large values (which seems to be the
case with amd64). The large value will be later used in de-referencing
nfsd4_layout_ops for function pointers.

Reported-by: Jani Tuovila <tuovila at synopsys.com>
Signed-off-by: Ari Kauppi <ari at synopsys.com>
[colin.king at canonical.com: use LAYOUT_TYPE_MAX instead of 32]
Cc: stable at vger.kernel.org
Reviewed-by: Dan Carpenter <dan.carpenter at oracle.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Signed-off-by: J. Bruce Fields <bfields at redhat.com>

Signed-off-by: Jianchuan Wang <jianchuan.wang at windriver.com>
---
 fs/nfsd/nfs4proc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 74a6e57..d76c944 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1255,7 +1255,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned int layout_type)
 		return NULL;
 	}
 
-	if (!(exp->ex_layout_types & (1 << layout_type))) {
+	if (layout_type >= LAYOUT_TYPE_MAX ||
+	    !(exp->ex_layout_types & (1 << layout_type))) {
 		dprintk("%s: layout type %d not supported\n",
 			__func__, layout_type);
 		return NULL;
-- 
2.8.1