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    Subject[PATCH 5.9 018/152] smb3: Handle error case during offload read path
    Date
    From: Rohith Surabattula <rohiths@microsoft.com>

    commit 1254100030b3377e8302f9c75090ab191d73ee7c upstream.

    Mid callback needs to be called only when valid data is
    read into pages.

    These patches address a problem found during decryption offload:
    CIFS: VFS: trying to dequeue a deleted mid
    that could cause a refcount use after free:
    Workqueue: smb3decryptd smb2_decrypt_offload [cifs]

    Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
    Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
    CC: Stable <stable@vger.kernel.org> #5.4+
    Signed-off-by: Steve French <stfrench@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/cifs/smb2ops.c | 20 +++++++++++++++++++-
    1 file changed, 19 insertions(+), 1 deletion(-)

    --- a/fs/cifs/smb2ops.c
    +++ b/fs/cifs/smb2ops.c
    @@ -4415,7 +4415,25 @@ static void smb2_decrypt_offload(struct
    dw->server->vals->read_rsp_size,
    dw->ppages, dw->npages, dw->len,
    true);
    - mid->callback(mid);
    + if (rc >= 0) {
    +#ifdef CONFIG_CIFS_STATS2
    + mid->when_received = jiffies;
    +#endif
    + mid->callback(mid);
    + } else {
    + spin_lock(&GlobalMid_Lock);
    + if (dw->server->tcpStatus == CifsNeedReconnect) {
    + mid->mid_state = MID_RETRY_NEEDED;
    + spin_unlock(&GlobalMid_Lock);
    + mid->callback(mid);
    + } else {
    + mid->mid_state = MID_REQUEST_SUBMITTED;
    + mid->mid_flags &= ~(MID_DELETED);
    + list_add_tail(&mid->qhead,
    + &dw->server->pending_mid_q);
    + spin_unlock(&GlobalMid_Lock);
    + }
    + }
    cifs_mid_q_entry_release(mid);
    }


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