[PATCH 5.18 0989/1095] firmware: arm_scpi: Ensure scpi_info is not assigned if the probe fails

Greg Kroah-Hartman
2022-08-15T23:19:44Z

From: Sudeep Holla <sudeep.holla@arm.com>

[ Upstream commit 689640efc0a2c4e07e6f88affe6d42cd40cc3f85 ]

When scpi probe fails, at any point, we need to ensure that the scpi_info
is not set and will remain NULL until the probe succeeds. If it is not
taken care, then it could result use-after-free as the value is exported
via get_scpi_ops() and could refer to a memory allocated via devm_kzalloc()
but freed when the probe fails.

Link: https://lore.kernel.org/r/20220701160310.148344-1-sudeep.holla@arm.com
Cc: stable@vger.kernel.org # 4.19+
Reported-by: huhai <huhai@kylinos.cn>
Reviewed-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/firmware/arm_scpi.c | 61 +++++++++++++++++++++----------------
1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index ddf0b9ff9e15..435d0e2658a4 100644
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -815,7 +815,7 @@ static int scpi_init_versions(struct scpi_drvinfo *info)
info->firmware_version = le32_to_cpu(caps.platform_version);
}
/* Ignore error if not implemented */
- if (scpi_info->is_legacy && ret == -EOPNOTSUPP)
+ if (info->is_legacy && ret == -EOPNOTSUPP)
return 0;

return ret;
@@ -913,13 +913,14 @@ static int scpi_probe(struct platform_device *pdev)
struct resource res;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
+ struct scpi_drvinfo *scpi_drvinfo;

- scpi_info = devm_kzalloc(dev, sizeof(*scpi_info), GFP_KERNEL);
- if (!scpi_info)
+ scpi_drvinfo = devm_kzalloc(dev, sizeof(*scpi_drvinfo), GFP_KERNEL);
+ if (!scpi_drvinfo)
return -ENOMEM;

if (of_match_device(legacy_scpi_of_match, &pdev->dev))
- scpi_info->is_legacy = true;
+ scpi_drvinfo->is_legacy = true;

count = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
if (count < 0) {
@@ -927,19 +928,19 @@ static int scpi_probe(struct platform_device *pdev)
return -ENODEV;
}

- scpi_info->channels = devm_kcalloc(dev, count, sizeof(struct scpi_chan),
- GFP_KERNEL);
- if (!scpi_info->channels)
+ scpi_drvinfo->channels =
+ devm_kcalloc(dev, count, sizeof(struct scpi_chan), GFP_KERNEL);
+ if (!scpi_drvinfo->channels)
return -ENOMEM;

- ret = devm_add_action(dev, scpi_free_channels, scpi_info);
+ ret = devm_add_action(dev, scpi_free_channels, scpi_drvinfo);
if (ret)
return ret;

- for (; scpi_info->num_chans < count; scpi_info->num_chans++) {
+ for (; scpi_drvinfo->num_chans < count; scpi_drvinfo->num_chans++) {
resource_size_t size;
- int idx = scpi_info->num_chans;
- struct scpi_chan *pchan = scpi_info->channels + idx;
+ int idx = scpi_drvinfo->num_chans;
+ struct scpi_chan *pchan = scpi_drvinfo->channels + idx;
struct mbox_client *cl = &pchan->cl;
struct device_node *shmem = of_parse_phandle(np, "shmem", idx);

@@ -986,45 +987,53 @@ static int scpi_probe(struct platform_device *pdev)
return ret;
}

- scpi_info->commands = scpi_std_commands;
+ scpi_drvinfo->commands = scpi_std_commands;

- platform_set_drvdata(pdev, scpi_info);
+ platform_set_drvdata(pdev, scpi_drvinfo);

- if (scpi_info->is_legacy) {
+ if (scpi_drvinfo->is_legacy) {
/* Replace with legacy variants */
scpi_ops.clk_set_val = legacy_scpi_clk_set_val;
- scpi_info->commands = scpi_legacy_commands;
+ scpi_drvinfo->commands = scpi_legacy_commands;

/* Fill priority bitmap */
for (idx = 0; idx < ARRAY_SIZE(legacy_hpriority_cmds); idx++)
set_bit(legacy_hpriority_cmds[idx],
- scpi_info->cmd_priority);
+ scpi_drvinfo->cmd_priority);
}

- ret = scpi_init_versions(scpi_info);
+ scpi_info = scpi_drvinfo;
+
+ ret = scpi_init_versions(scpi_drvinfo);
if (ret) {
dev_err(dev, "incorrect or no SCP firmware found\n");
+ scpi_info = NULL;
return ret;
}

- if (scpi_info->is_legacy && !scpi_info->protocol_version &&
- !scpi_info->firmware_version)
+ if (scpi_drvinfo->is_legacy && !scpi_drvinfo->protocol_version &&
+ !scpi_drvinfo->firmware_version)
dev_info(dev, "SCP Protocol legacy pre-1.0 firmware\n");
else
dev_info(dev, "SCP Protocol %lu.%lu Firmware %lu.%lu.%lu version\n",
FIELD_GET(PROTO_REV_MAJOR_MASK,
- scpi_info->protocol_version),
+ scpi_drvinfo->protocol_version),
FIELD_GET(PROTO_REV_MINOR_MASK,
- scpi_info->protocol_version),
+ scpi_drvinfo->protocol_version),
FIELD_GET(FW_REV_MAJOR_MASK,
- scpi_info->firmware_version),
+ scpi_drvinfo->firmware_version),
FIELD_GET(FW_REV_MINOR_MASK,
- scpi_info->firmware_version),
+ scpi_drvinfo->firmware_version),
FIELD_GET(FW_REV_PATCH_MASK,
- scpi_info->firmware_version));
- scpi_info->scpi_ops = &scpi_ops;
+ scpi_drvinfo->firmware_version));
+
+ scpi_drvinfo->scpi_ops = &scpi_ops;

- return devm_of_platform_populate(dev);
+ ret = devm_of_platform_populate(dev);
+ if (ret)
+ scpi_info = NULL;
+
+ return ret;
}

static const struct of_device_id scpi_of_match[] = {
--
2.35.1