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Subject[PATCH] firmware: arm_scmi: Fix late checks on pointer dereference
Date
A few dereferences could happen before the iterator pointer argument was
checked for NULL, causing the following smatch warnings:

drivers/firmware/arm_scmi/driver.c:1214 scmi_iterator_run() warn: variable
dereferenced before check 'i' (see line 1210)

Fix by moving the checks early and dropping some unneeded local references.

No functional change.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
drivers/firmware/arm_scmi/driver.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index c4960fd3df75..c1922bd650ae 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1205,18 +1205,21 @@ static void *scmi_iterator_init(const struct scmi_protocol_handle *ph,
static int scmi_iterator_run(void *iter)
{
int ret = -EINVAL;
+ struct scmi_iterator_ops *iops;
+ const struct scmi_protocol_handle *ph;
+ struct scmi_iterator_state *st;
struct scmi_iterator *i = iter;
- struct scmi_iterator_state *st = &i->state;
- struct scmi_iterator_ops *iops = i->ops;
- const struct scmi_protocol_handle *ph = i->ph;
- const struct scmi_xfer_ops *xops = ph->xops;

- if (!i)
+ if (!i || !i->ops || !i->ph)
return ret;

+ iops = i->ops;
+ ph = i->ph;
+ st = &i->state;
+
do {
iops->prepare_message(i->msg, st->desc_index, i->priv);
- ret = xops->do_xfer(ph, i->t);
+ ret = ph->xops->do_xfer(ph, i->t);
if (ret)
break;

@@ -1240,7 +1243,7 @@ static int scmi_iterator_run(void *iter)
}

st->desc_index += st->num_returned;
- xops->reset_rx_to_maxsz(ph, i->t);
+ ph->xops->reset_rx_to_maxsz(ph, i->t);
/*
* check for both returned and remaining to avoid infinite
* loop due to buggy firmware
@@ -1249,7 +1252,7 @@ static int scmi_iterator_run(void *iter)

out:
/* Finalize and destroy iterator */
- xops->xfer_put(ph, i->t);
+ ph->xops->xfer_put(ph, i->t);
devm_kfree(ph->dev, i);

return ret;
--
2.32.0
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