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SubjectRe: arm64: libgpiod: refcount_t: underflow; use-after-free.
On Mon, Feb 20, 2023 at 08:29:27PM +0530, Naresh Kamboju wrote:
> Following kernel warning notices on qemu-arm64, qemu-arm and also on devices
> running Linux version v6.2.0 while running libgpiod tests.
>
> + ./gpiod.sh /opt/libgpiod/bin/
> [INFO] libgpiod test suite
> [INFO] 117 tests registered
> [INFO] checking the linux kernel version
> [INFO] kernel release is v6.2.0 - ok to run tests
> [INFO] using gpio-tools from '/usr/bin'
> [ 10.499036] ------------[ cut here ]------------
> [ 10.499656] refcount_t: underflow; use-after-free.
> [ 10.500264] WARNING: CPU: 2 PID: 291 at lib/refcount.c:28
> refcount_warn_saturate+0xf4/0x144
> [ 10.501306] Modules linked in: gpio_mockup(-) cfg80211 bluetooth
> rfkill crct10dif_ce fuse drm
> [ 10.502364] CPU: 2 PID: 291 Comm: gpiod-test Not tainted 6.2.0 #1
> [ 10.503229] Hardware name: linux,dummy-virt (DT)
> [ 10.503883] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 10.505331] pc : refcount_warn_saturate+0xf4/0x144
> [ 10.505723] lr : refcount_warn_saturate+0xf4/0x144
> [ 10.506115] sp : ffff800008983cd0
> [ 10.506391] x29: ffff800008983cd0 x28: ffff0000c4c4c100 x27: 0000000000000000
> [ 10.506961] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
> [ 10.507533] x23: 0000000000000200 x22: ffff0000c4e66800 x21: ffff0000c7734640
> [ 10.508104] x20: 0000000000000001 x19: ffff0000c7734600 x18: ffffffffffffffff
> [ 10.508677] x17: 3d4d455453595342 x16: ffffcf0234432020 x15: ffff800088983957
> [ 10.509424] x14: 0000000000000000 x13: 2e656572662d7265 x12: 7466612d65737520
> [ 10.510003] x11: 3b776f6c66726564 x10: ffffcf02365db580 x9 : ffffcf0233b20138
> [ 10.510575] x8 : 00000000ffffefff x7 : ffffcf02365db580 x6 : 0000000000000001
> [ 10.511145] x5 : ffffcf023655f000 x4 : ffffcf023655f2e8 x3 : 0000000000000000
> [ 10.511721] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000c4c4c100
> [ 10.512294] Call trace:
> [ 10.512494] refcount_warn_saturate+0xf4/0x144
> [ 10.512971] kobject_put+0x164/0x220
> [ 10.513224] fwnode_remove_software_node+0x44/0x60
> [ 10.513554] gpio_mockup_unregister_pdevs+0x54/0x70 [gpio_mockup]
> [ 10.513970] gpio_mockup_exit+0x10/0x328 [gpio_mockup]
> [ 10.514322] __arm64_sys_delete_module+0x190/0x2a0
> [ 10.514653] invoke_syscall+0x50/0x120
> [ 10.514915] el0_svc_common.constprop.0+0x104/0x124
> [ 10.515277] do_el0_svc+0x44/0xcc
> [ 10.515541] el0_svc+0x30/0x94
> [ 10.515788] el0t_64_sync_handler+0xbc/0x13c
> [ 10.516126] el0t_64_sync+0x190/0x194
> [ 10.516419] ---[ end trace 0000000000000000 ]---
>
>
> Build and test logs,
> https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v6.2/testrun/14856342/suite/libgpiod/test/ctxless-get-value-single-line/log
> https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v6.2/testrun/14856342/suite/libgpiod/tests/

Can you give a try of the patch below?

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 77510e4f47de..1807678f032b 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -557,7 +557,7 @@ static void platform_device_release(struct device *dev)
struct platform_object *pa = container_of(dev, struct platform_object,
pdev.dev);

- of_node_put(pa->pdev.dev.of_node);
+ fwnode_handle_put(dev_fwnode(&pa->pdev.dev));
kfree(pa->pdev.dev.platform_data);
kfree(pa->pdev.mfd_cell);
kfree(pa->pdev.resource);
@@ -814,8 +814,7 @@ struct platform_device *platform_device_register_full(
return ERR_PTR(-ENOMEM);

pdev->dev.parent = pdevinfo->parent;
- pdev->dev.fwnode = pdevinfo->fwnode;
- pdev->dev.of_node = of_node_get(to_of_node(pdev->dev.fwnode));
+ device_set_node(&pdev->dev, fwnode_handle_get(pdevinfo->fwnode));
pdev->dev.of_node_reused = pdevinfo->of_node_reused;

if (pdevinfo->dma_mask) {
@@ -844,8 +843,8 @@ struct platform_device *platform_device_register_full(
ret = platform_device_add(pdev);
if (ret) {
err:
- ACPI_COMPANION_SET(&pdev->dev, NULL);
platform_device_put(pdev);
+ fwnode_handle_put(pdevinfo->fwnode);
return ERR_PTR(ret);
}

--
With Best Regards,
Andy Shevchenko

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