Re: [PATCH] scsi: be2iscsi: Fix a use after free in beiscsi_if_clr_ip

[Martin K. Petersen]

Lv,

> In the free_cmd error path of callee beiscsi_exec_nemb_cmd(),
> nonemb_cmd->va is freed by dma_free_coherent().  As req =
> nonemb_cmd.va, we can see that the freed nonemb_cmd.va is still
> dereferenced and used by req->ip_params.ip_record.status.

> My patch uses status to replace req->ip_params.ip_record.status to
> avoid the uaf.

This status is captured prior to executing the command so it doesn't
actually reflect whether the operation was successful (which I believe
was the intent).

Some of the callers of beiscsi_exec_nemb_cmd() pass a response buffer
and a response length as the two last arguments. Since
beiscsi_exec_nemb_cmd() frees the command before returning, passing a
response buffer seems to be the only way to get meaningful data out.

I am not sure whether the OPCODE_COMMON_ISCSI_NTWK_MODIFY_IP_ADDR
operation returns something useful from the controller. As far as I can
tell not all operations have a response buffer defined.

My recommendation would be to add a response buffer and try to decipher
what comes back from the firmware. Also, beiscsi_if_set_ip() appears to
have the same problem as beiscsi_if_clr_ip().

-- 
Martin K. Petersen	Oracle Linux Engineering