linux-kernel - [PATCH 4.9 072/199] fuse: verify nlink

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Message-Id: <20191219183218.970919427@linuxfoundation.org>
Date:   Thu, 19 Dec 2019 19:32:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miklos Szeredi <mszeredi@...hat.com>
Subject: [PATCH 4.9 072/199] fuse: verify nlink

From: Miklos Szeredi <mszeredi@...hat.com>

commit c634da718db9b2fac201df2ae1b1b095344ce5eb upstream.

When adding a new hard link, make sure that i_nlink doesn't overflow.

Fixes: ac45d61357e8 ("fuse: fix nlink after unlink")
Cc: <stable@...r.kernel.org> # v3.4
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/fuse/dir.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -830,7 +830,8 @@ static int fuse_link(struct dentry *entr
 
 		spin_lock(&fc->lock);
 		fi->attr_version = ++fc->attr_version;
-		inc_nlink(inode);
+		if (likely(inode->i_nlink < UINT_MAX))
+			inc_nlink(inode);
 		spin_unlock(&fc->lock);
 		fuse_invalidate_attr(inode);
 		fuse_update_ctime(inode);