[PATCH AUTOSEL 5.10 06/13] scsi: qla2xxx: Fix unmap of already freed sgl

Sasha Levin
2021-10-25T17:01:18Z

From: Dmitry Bogdanov <d.bogdanov@yadro.com>

[ Upstream commit 4a8f71014b4d56c4fb287607e844c0a9f68f46d9 ]

The sgl is freed in the target stack in target_release_cmd_kref() before
calling qlt_free_cmd() but there is an unmap of sgl in qlt_free_cmd() that
causes a panic if sgl is not yet DMA unmapped:

NIP dma_direct_unmap_sg+0xdc/0x180
LR dma_direct_unmap_sg+0xc8/0x180
Call Trace:
ql_dbg_prefix+0x68/0xc0 [qla2xxx] (unreliable)
dma_unmap_sg_attrs+0x54/0xf0
qlt_unmap_sg.part.19+0x54/0x1c0 [qla2xxx]
qlt_free_cmd+0x124/0x1d0 [qla2xxx]
tcm_qla2xxx_release_cmd+0x4c/0xa0 [tcm_qla2xxx]
target_put_sess_cmd+0x198/0x370 [target_core_mod]
transport_generic_free_cmd+0x6c/0x1b0 [target_core_mod]
tcm_qla2xxx_complete_free+0x6c/0x90 [tcm_qla2xxx]

The sgl may be left unmapped in error cases of response sending. For
instance, qlt_rdy_to_xfer() maps sgl and exits when session is being
deleted keeping the sgl mapped.

This patch removes use-after-free of the sgl and ensures that the sgl is
unmapped for any command that was not sent to firmware.

Link: https://lore.kernel.org/r/20211018122650.11846-1-d.bogdanov@yadro.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/qla2xxx/qla_target.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index 8d4976725a75..ebed14bed783 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -3256,8 +3256,7 @@ int qlt_xmit_response(struct qla_tgt_cmd *cmd, int xmit_type,
"RESET-RSP online/active/old-count/new-count = %d/%d/%d/%d.\n",
vha->flags.online, qla2x00_reset_active(vha),
cmd->reset_count, qpair->chip_reset);
- spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
- return 0;
+ goto out_unmap_unlock;
}

/* Does F/W have an IOCBs for this request */
@@ -3380,10 +3379,6 @@ int qlt_rdy_to_xfer(struct qla_tgt_cmd *cmd)
prm.sg = NULL;
prm.req_cnt = 1;

- /* Calculate number of entries and segments required */
- if (qlt_pci_map_calc_cnt(&prm) != 0)
- return -EAGAIN;
-
if (!qpair->fw_started || (cmd->reset_count != qpair->chip_reset) ||
(cmd->sess && cmd->sess->deleted)) {
/*
@@ -3401,6 +3396,10 @@ int qlt_rdy_to_xfer(struct qla_tgt_cmd *cmd)
return 0;
}

+ /* Calculate number of entries and segments required */
+ if (qlt_pci_map_calc_cnt(&prm) != 0)
+ return -EAGAIN;
+
spin_lock_irqsave(qpair->qp_lock_ptr, flags);
/* Does F/W have an IOCBs for this request */
res = qlt_check_reserve_free_req(qpair, prm.req_cnt);
@@ -3805,9 +3804,6 @@ void qlt_free_cmd(struct qla_tgt_cmd *cmd)

BUG_ON(cmd->cmd_in_wq);

- if (cmd->sg_mapped)
- qlt_unmap_sg(cmd->vha, cmd);
-
if (!cmd->q_full)
qlt_decr_num_pend_cmds(cmd->vha);

--
2.33.0