From a7705157664b489cd280b5ab1c384ede66043ed1 Mon Sep 17 00:00:00 2001 From: Ari Kauppi Date: Fri, 5 May 2017 16:07:55 -0400 Subject: [PATCH] nfsd: fix undefined behavior in nfsd4_layout_verify 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 Signed-off-by: Ari Kauppi [colin.king@canonical.com: use LAYOUT_TYPE_MAX instead of 32] Cc: stable@vger.kernel.org Reviewed-by: Dan Carpenter Reviewed-by: Christoph Hellwig Signed-off-by: J. Bruce Fields (cherry picked from commit b550a32e60a4941994b437a8d662432a486235a5) Orabug: 26376568 CVE: CVE-2017-8797 Signed-off-by: Kirtikar Kashyap Reviewed-by: Jack Vogel Conflicts: fs/nfsd/nfs4proc.c --- 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 2b50bc0c545e..75cca7e38ce2 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1194,7 +1194,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned int layout_type) return NULL; } - if (exp->ex_layout_type != layout_type) { + if (layout_type >= LAYOUT_TYPE_MAX || + (exp->ex_layout_type != layout_type)) { dprintk("%s: layout type %d not supported\n", __func__, layout_type); return NULL; -- 2.50.1