3.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Nicholas Bellinger <n...@linux-iscsi.org> commit 4c054ba63ad47ef244cfcfa1cea38134620a5bae upstream. This patch fixes a long-standing bug with SCSI overflow handling where se_cmd->data_length was incorrectly being re-assigned to the larger CDB extracted allocation length, resulting in a number of fabric level errors that would end up causing a session reset in most cases. So instead now: - Only re-assign se_cmd->data_length durining UNDERFLOW (to use the smaller value) - Use existing se_cmd->data_length for OVERFLOW (to use the smaller value) This fix has been tested with the following CDB to generate an SCSI overflow: sg_raw -r512 /dev/sdc 28 0 0 0 0 0 0 0 9 0 Tested using iscsi-target, tcm_qla2xxx, loopback and tcm_vhost fabric ports. Here is a bit more detail on each case: - iscsi-target: Bug with open-iscsi with overflow, sg_raw returns -3584 bytes of data. - tcm_qla2xxx: Working as expected, returnins 512 bytes of data - loopback: sg_raw returns CHECK_CONDITION, from overflow rejection in transport_generic_map_mem_to_cmd() - tcm_vhost: Same as loopback Reported-by: Roland Dreier <rol...@purestorage.com> Cc: Roland Dreier <rol...@purestorage.com> Cc: Christoph Hellwig <h...@lst.de> Cc: Boaz Harrosh <bharr...@panasas.com> Signed-off-by: Nicholas Bellinger <n...@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/target/target_core_transport.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -3167,15 +3167,20 @@ static int transport_generic_cmd_sequenc /* Returns CHECK_CONDITION + INVALID_CDB_FIELD */ goto out_invalid_cdb_field; } - + /* + * For the overflow case keep the existing fabric provided + * ->data_length. Otherwise for the underflow case, reset + * ->data_length to the smaller SCSI expected data transfer + * length. + */ if (size > cmd->data_length) { cmd->se_cmd_flags |= SCF_OVERFLOW_BIT; cmd->residual_count = (size - cmd->data_length); } else { cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT; cmd->residual_count = (cmd->data_length - size); + cmd->data_length = size; } - cmd->data_length = size; } if (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB && -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/