Live › vulnerability › CVE-2026-98848
Go to dashboardIn the Linux RTC driver for the AC100 chip, the clock provider's element count was set after the array was already written, so kernels built with UBSAN bounds checking report an out-of-bounds access and trap at boot. The sources describe a crash or warning during probe on those builds, not a way for an attacker to run code.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Only kernels built with CONFIG_UBSAN_BOUNDS and a compiler that supports __counted_by (GCC 15.1+ or Clang 20.1+) hit the warning or trap, and only on hardware that uses the AC100 RTC driver. Production kernels without UBSAN bounds checking are not affected by the reported behavior.
No product ranges from the sources yet.
uname -r to get the running kernel version, then compare against the fixed stable kernel listed in the NVD entrygrep -i ubsan /boot/config-$(uname -r) to see whether CONFIG_UBSAN_BOUNDS or CONFIG_UBSAN_TRAP is enabledEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
rtc: ac100: Assign .num before accessing .hws
Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with __counted_by") annotated the hws member of 'struct clk_hw_onecell_data' with __counted_by, which informs the bounds sanitizer (UBSAN_BOUNDS) about the number of elements in .hws[], so that it can warn when .hws[] is accessed out of bounds. As noted in that change, the __counted_by member must be initialized with the number of elements before the first array access happens, otherwise there will be a warning from each access prior to the initialization because the number of elements is zero. This occurs in ac100_rtc_register_clks() due to .num being assigned only after every clkout clock has been stored in .hws[]. With CONFIG_UBSAN_BOUNDS and a compiler that implements __counted_by (GCC 15.1+ or Clang 20.1+), this triggers an array-index-out-of-bounds report during probe, and with CONFIG_UBSAN_TRAP the first store traps.
Initialize .num with AC100_CLKOUT_NUM, the number of elements .hws[] was allocated with, right after the allocation. That is the value the loop counter ends up at on the success path anyway, so the provider's behaviour is unchanged.
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