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Subject[PATCH] firmware: arm_scpi: Fix error handle when scpi probe failed
Date
From: huhai <huhai@kylinos.cn>

When scpi probe fails, do not just return the error code, but also reset
the global scpi_info to NULL, otherwise scpi_hwmon_probe() may get a UAF
and cause panic:

scpi_protocol FTSC0001:00: incorrect or no SCP firmware found
... ...
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
ESR = 0x86000005
Exception class = IABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
user pgtable: 64k pages, 48-bit VAs, pgdp = (____ptrval____)
[0000000000000000] pgd=0000000000000000, pud=0000000000000000
Internal error: Oops: 86000005 [#1] SMP
... ...
pc : (null)
lr : scpi_hwmon_probe+0x2c/0x4bc [scpi_hwmon]
sp : ffff801fa13cfb20
x29: ffff801fa13cfb20 x28: ffff00000931c1e8
x27: ffff0000093b7318 x26: 000000000000000d
x25: ffff801fa1174da8 x24: 0000000000000000
x23: ffff801fa15e9000 x22: 0000000000000000
x21: ffff0000012c0028 x20: ffff801fa15e9010
x19: 0000000000000000 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000
x15: 0000000000000400 x14: 0000000000000400
x13: 0000000000000001 x12: 0000000000000018
x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f
x9 : fefefefeff2f2f39 x8 : 7f7f7f7f7f7f7f7f
x7 : 302f2f2f52525345 x6 : ffff801fa5771a8c
x5 : 0000000000000000 x4 : 0000000000000000
x3 : ffff801fa13bbc00 x2 : ffff000009360118
x1 : 0000000000000000 x0 : ffff801fa13cfbbe
Call trace:
(null)
platform_drv_probe+0x50/0xa0
really_probe+0x240/0x420
driver_probe_device+0x68/0x134
__device_attach_driver+0xb8/0x130
bus_for_each_drv+0x64/0xa0
__device_attach+0xa8/0x194
device_initial_probe+0x10/0x1c
bus_probe_device+0x90/0xa0
deferred_probe_work_func+0x90/0xe0
process_one_work+0x1c0/0x390
worker_thread+0x6c/0x384
kthread+0xfc/0x12c
ret_from_fork+0x10/0x18
Code: bad PC value
---[ end trace b4b2f27a69b5712c ]---

Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: huhai <huhai@kylinos.cn>
---
drivers/firmware/arm_scpi.c | 36 +++++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index ddf0b9ff9e15..ad2355814bdf 100644
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -924,17 +924,20 @@ static int scpi_probe(struct platform_device *pdev)
count = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
if (count < 0) {
dev_err(dev, "no mboxes property in '%pOF'\n", np);
- return -ENODEV;
+ ret = -ENODEV;
+ goto err;
}

scpi_info->channels = devm_kcalloc(dev, count, sizeof(struct scpi_chan),
GFP_KERNEL);
- if (!scpi_info->channels)
- return -ENOMEM;
+ if (!scpi_info->channels) {
+ ret = -ENOMEM;
+ goto err;
+ }

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

for (; scpi_info->num_chans < count; scpi_info->num_chans++) {
resource_size_t size;
@@ -943,21 +946,24 @@ static int scpi_probe(struct platform_device *pdev)
struct mbox_client *cl = &pchan->cl;
struct device_node *shmem = of_parse_phandle(np, "shmem", idx);

- if (!of_match_node(shmem_of_match, shmem))
- return -ENXIO;
+ if (!of_match_node(shmem_of_match, shmem)) {
+ ret = -ENXIO;
+ goto err;
+ }

ret = of_address_to_resource(shmem, 0, &res);
of_node_put(shmem);
if (ret) {
dev_err(dev, "failed to get SCPI payload mem resource\n");
- return ret;
+ goto err;
}

size = resource_size(&res);
pchan->rx_payload = devm_ioremap(dev, res.start, size);
if (!pchan->rx_payload) {
dev_err(dev, "failed to ioremap SCPI payload\n");
- return -EADDRNOTAVAIL;
+ ret = -EADDRNOTAVAIL;
+ goto err;
}
pchan->tx_payload = pchan->rx_payload + (size >> 1);

@@ -983,7 +989,7 @@ static int scpi_probe(struct platform_device *pdev)
dev_err(dev, "failed to get channel%d err %d\n",
idx, ret);
}
- return ret;
+ goto err;
}

scpi_info->commands = scpi_std_commands;
@@ -1004,7 +1010,7 @@ static int scpi_probe(struct platform_device *pdev)
ret = scpi_init_versions(scpi_info);
if (ret) {
dev_err(dev, "incorrect or no SCP firmware found\n");
- return ret;
+ goto err;
}

if (scpi_info->is_legacy && !scpi_info->protocol_version &&
@@ -1024,7 +1030,15 @@ static int scpi_probe(struct platform_device *pdev)
scpi_info->firmware_version));
scpi_info->scpi_ops = &scpi_ops;

- return devm_of_platform_populate(dev);
+ ret = devm_of_platform_populate(dev);
+ if (ret)
+ goto err;
+
+ return ret;
+err:
+ /* stop exporting SCPI ops through get_scpi_ops */
+ scpi_info = NULL;
+ return ret;
}

static const struct of_device_id scpi_of_match[] = {
--
2.27.0
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