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    Subject[PATCH 5.0 56/89] NFS: Forbid setting AF_INET6 to "struct sockaddr_in"->sin_family.
    Date
    From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

    commit 7c2bd9a39845bfb6d72ddb55ce737650271f6f96 upstream.

    syzbot is reporting uninitialized value at rpc_sockaddr2uaddr() [1]. This
    is because syzbot is setting AF_INET6 to "struct sockaddr_in"->sin_family
    (which is embedded into user-visible "struct nfs_mount_data" structure)
    despite nfs23_validate_mount_data() cannot pass sizeof(struct sockaddr_in6)
    bytes of AF_INET6 address to rpc_sockaddr2uaddr().

    Since "struct nfs_mount_data" structure is user-visible, we can't change
    "struct nfs_mount_data" to use "struct sockaddr_storage". Therefore,
    assuming that everybody is using AF_INET family when passing address via
    "struct nfs_mount_data"->addr, reject if its sin_family is not AF_INET.

    [1] https://syzkaller.appspot.com/bug?id=599993614e7cbbf66bc2656a919ab2a95fb5d75c

    Reported-by: syzbot <syzbot+047a11c361b872896a4f@syzkaller.appspotmail.com>
    Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- a/fs/nfs/super.c
    +++ b/fs/nfs/super.c
    @@ -2041,7 +2041,8 @@ static int nfs23_validate_mount_data(voi
    memcpy(sap, &data->addr, sizeof(data->addr));
    args->nfs_server.addrlen = sizeof(data->addr);
    args->nfs_server.port = ntohs(data->addr.sin_port);
    - if (!nfs_verify_server_address(sap))
    + if (sap->sa_family != AF_INET ||
    + !nfs_verify_server_address(sap))
    goto out_no_address;

    if (!(data->flags & NFS_MOUNT_TCP))

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