Linux kernel ac100 RTC driver UAF on probe failure
CVE-2026-98826 Published on October 18, 2026
rtc: ac100: Fix clock provider use-after-free on probe failure
In the Linux kernel, the following vulnerability has been resolved:
rtc: ac100: Fix clock provider use-after-free on probe failure
ac100_rtc_register_clks() registers the RTC-32k clock with
clk_hw_register_fixed_rate() and the clock provider with
of_clk_add_hw_provider(). Neither is device managed, and both are
released only from ac100_rtc_remove(). The driver core does not call
remove() when probe() fails: really_probe() reaches probe_failed below
the device_remove() call and goes straight to releasing the device's
managed resources.
ac100_rtc_probe() ends with
return devm_rtc_register_device(chip->rtc);
so if that fails after the clocks have been registered, the provider is
left on the global of_clk_providers list holding chip->clk_data, which
was allocated with devm_kzalloc() and is freed while probe() unwinds. A
later lookup on this device tree node then reads freed memory in
of_clk_hw_onecell_get(). Consumers that do exactly that exist in tree:
the wifi power sequence nodes on sun8i-a83t-bananapi-m3 and
sun8i-a83t-cubietruck-plus take <&ac100_rtc 1>, and the sun9i-a80 boards
route osc32k through <&ac100_rtc 0>. The window is narrow, as
devm_rtc_register_device() can only fail with -ENOMEM here, but the
provider is left dangling whenever it does.
The RTC-32k clock is leaked on the same path. Since clk_core_lookup()
searches a global list that is not scoped per device, __clk_register()
rejects the duplicate name with -EEXIST, so the leak also makes a later
probe of the same device fail.
The error path that returns -EINVAL when the ADDA 4M parent clock cannot
be found leaks the RTC-32k clock in the same way. No provider has been
registered at that point, so that one is a leak rather than a
use-after-free.
Register both with devm_clk_hw_register_fixed_rate() and
devm_of_clk_add_hw_provider() so that they are released whenever the
device goes away, on a failed probe as well as on unbind. Devres
releases in reverse order of acquisition, so the provider is removed
before chip->clk_data is freed, and the clkout children are now
unregistered before their parent rather than after it.
ac100_rtc_unregister_clks() and the remove callback then have nothing
left to do and are removed.
Products Associated with CVE-2026-98826
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Affected Versions
Linux:- Version d00a18a42c1483924de086ddfb0efe8da1dba3ac and below 12bcd20d76703ee2baf52224d287b7fea096b12f is affected.
- Version d00a18a42c1483924de086ddfb0efe8da1dba3ac and below 9cff19ddd7f90c1f572a0f83cfc41de8f8dcbcd8 is affected.
- Version d00a18a42c1483924de086ddfb0efe8da1dba3ac and below 55ca60ba336632349f7c4585d22ba74ae355b7ce is affected.
- Version d00a18a42c1483924de086ddfb0efe8da1dba3ac and below fcf0b58e976e83adf246b014518e49c662b96f5e is affected.
- Version 4.9 is affected.
- Before 4.9 is unaffected.
- Version 6.12.113, <= 6.12.* is unaffected.
- Version 6.18.56, <= 6.18.* is unaffected.
- Version 7.2.10, <= 7.2.* is unaffected.
- Version 7.3-rc6, <= * is unaffected.