firmware: arm_scpi: Ensure scpi_info is not assigned if the probe fails

[ 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>

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index ddf0b9f..435d0e2 100644 (file)
--- 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[] = {