CVE-2026-98677iio: adc: ad_sigma_delta: fix use-after-free on unbind

Official description

In the Linux kernel, the following vulnerability has been resolved: iio: adc: ad_sigma_delta: fix use-after-free on unbind ad_sd_buffer_postenable() allocates sigma_delta->samples_buf with devm_krealloc() at runtime, so its devres entry sits after all probe-time entries of the driver. devm resources are released in reverse allocation order, which means unbind frees samples_buf before iio_device_unregister() disables the buffers and detaches the trigger pollfunc. The data ready IRQ is still enabled at that point, so ad_sd_trigger_handler() can still run and memcpy() incoming samples into the freed samples_buf. Fix this by preallocating the buffer in devm_ad_sd_setup_buffer_and_trigger(), before the triggered buffer and the IRQ are set up, so it is freed only after iio_device_unregister() has drained the trigger handler via free_irq(). Size it for the worst case of all sequencer slots being active; ad_sd_validate_scan_mask() already caps the number of active channels at num_slots. This issue was found by an in-house static analysis tool.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/b2a991d33f1e2207052fe745d1fe459db8b365e2
• https://git.kernel.org/stable/c/975b09bc680acc60903777b766cdb53b0bf9c9f6
• https://git.kernel.org/stable/c/84500ae0d976995a6870cb1dca2d124b6b2d6e5a
• https://git.kernel.org/stable/c/f20b94a7dc1ff9ade191ce839c984210fdbdc653
• https://git.kernel.org/stable/c/5663c72bf400231e90777982216797191887a6b9
• https://git.kernel.org/stable/c/9ee8306121495d2a25aa5d1bfd519f2748786b83