[PATCH] nfs: Fix potential posix_acl refcnt leak in nfs3_set_acl

From: Andreas Gruenbacher <agruenba@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
	"okir@suse.de" <okir@suse.de>,
	"tanxin.ctf@gmail.com" <tanxin.ctf@gmail.com>,
	"xiyuyang19@fudan.edu.cn" <xiyuyang19@fudan.edu.cn>,
	"akpm@osdl.org" <akpm@osdl.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
	"kjlu@umn.edu" <kjlu@umn.edu>,
	"yuanxzhang@fudan.edu.cn" <yuanxzhang@fudan.edu.cn>
Subject: [PATCH] nfs: Fix potential posix_acl refcnt leak in nfs3_set_acl
Date: Mon, 20 Apr 2020 15:51:47 +0200	[thread overview]
Message-ID: <20200420135147.21572-1-agruenba@redhat.com> (raw)

nfs3_set_acl keeps track of the acl it allocated locally to determine if an acl
needs to be released at the end.  This results in a memory leak when the
function allocates an acl as well as a default acl.  Fix by releasing acls
that differ from the acl originally passed into nfs3_set_acl.

Fixes: b7fa0554cf1b ("[PATCH] NFS: Add support for NFSv3 ACLs")
Reported-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/nfs/nfs3acl.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index c5c3fc6e6c60..26c94b32d6f4 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -253,37 +253,45 @@ int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 
 int nfs3_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 {
-	struct posix_acl *alloc = NULL, *dfacl = NULL;
+	struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
 	int status;
 
 	if (S_ISDIR(inode->i_mode)) {
 		switch(type) {
 		case ACL_TYPE_ACCESS:
-			alloc = dfacl = get_acl(inode, ACL_TYPE_DEFAULT);
+			alloc = get_acl(inode, ACL_TYPE_DEFAULT);
 			if (IS_ERR(alloc))
 				goto fail;
+			dfacl = alloc;
 			break;
 
 		case ACL_TYPE_DEFAULT:
-			dfacl = acl;
-			alloc = acl = get_acl(inode, ACL_TYPE_ACCESS);
+			alloc = get_acl(inode, ACL_TYPE_ACCESS);
 			if (IS_ERR(alloc))
 				goto fail;
+			dfacl = acl;
+			acl = alloc;
 			break;
 		}
 	}
 
 	if (acl == NULL) {
-		alloc = acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
+		alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
 		if (IS_ERR(alloc))
 			goto fail;
+		acl = alloc;
 	}
 	status = __nfs3_proc_setacls(inode, acl, dfacl);
-	posix_acl_release(alloc);
+out:
+	if (acl != orig)
+		posix_acl_release(acl);
+	if (dfacl != orig)
+		posix_acl_release(dfacl);
 	return status;
 
 fail:
-	return PTR_ERR(alloc);
+	status = PTR_ERR(alloc);
+	goto out;
 }
 
 const struct xattr_handler *nfs3_xattr_handlers[] = {

base-commit: ae83d0b416db002fe95601e7f97f64b59514d936
-- 
2.25.3

