[PATCH 6.8 037/172] cxl/core: Fix initialization of mbox_cmd.size_out in get event

Greg Kroah-Hartman
2024-04-15T14:25:15Z

From: Kwangjin Ko <kwangjin.ko@sk.com>

[ Upstream commit f7c52345ccc96343c0a05bdea3121c8ac7b67d5f ]

Since mbox_cmd.size_out is overwritten with the actual output size in
the function below, it needs to be initialized every time.

cxl_internal_send_cmd -> __cxl_pci_mbox_send_cmd

Problem scenario:

1) The size_out variable is initially set to the size of the mailbox.
2) Read an event.
- size_out is set to 160 bytes(header 32B + one event 128B).
- Two event are created while reading.
3) Read the new *two* events.
- size_out is still set to 160 bytes.
- Although the value of out_len is 288 bytes, only 160 bytes are
copied from the mailbox register to the local variable.
- record_count is set to 2.
- Accessing records[1] will result in reading incorrect data.

Fixes: 6ebe28f9ec72 ("cxl/mem: Read, trace, and clear events on driver load")
Tested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Kwangjin Ko <kwangjin.ko@sk.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cxl/core/mbox.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 50146161887d5..f0f54aeccc872 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -958,13 +958,14 @@ static void cxl_mem_get_records_log(struct cxl_memdev_state *mds,
.payload_in = &log_type,
.size_in = sizeof(log_type),
.payload_out = payload,
- .size_out = mds->payload_size,
.min_out = struct_size(payload, records, 0),
};

do {
int rc, i;

+ mbox_cmd.size_out = mds->payload_size;
+
rc = cxl_internal_send_cmd(mds, &mbox_cmd);
if (rc) {
dev_err_ratelimited(dev,
--
2.43.0