linux-kernel - [PATCH 5.7 043/166] nfs: Fix memory leak of export

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Message-Id: <20200714184117.942167644@linuxfoundation.org>
Date:   Tue, 14 Jul 2020 20:43:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tom Rix <trix@...hat.com>,
        Anna Schumaker <Anna.Schumaker@...app.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 043/166] nfs: Fix memory leak of export_path

From: Tom Rix <trix@...hat.com>

[ Upstream commit 4659ed7cc8514369043053463514408ca16ad6f3 ]

The try_location function is called within a loop by nfs_follow_referral.
try_location calls nfs4_pathname_string to created the export_path.
nfs4_pathname_string allocates the memory. export_path is stored in the
nfs_fs_context/fs_context structure similarly as hostname and source.
But whereas the ctx hostname and source are freed before assignment,
export_path is not.  So if there are multiple loops, the new export_path
will overwrite the old without the old being freed.

So call kfree for export_path.

Signed-off-by: Tom Rix <trix@...hat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@...app.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/nfs/nfs4namespace.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
index a3ab6e219061b..873342308dc0d 100644
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -308,6 +308,7 @@ static int try_location(struct fs_context *fc,
 	if (IS_ERR(export_path))
 		return PTR_ERR(export_path);
 
+	kfree(ctx->nfs_server.export_path);
 	ctx->nfs_server.export_path = export_path;
 
 	source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
-- 
2.25.1