Executive brief
A vulnerability was identified in the Linux kernel's Spreadtrum EIC GPIO driver that could cause system instability or crashes on Real-Time (PREEMPT_RT) Linux configurations. The issue occurs when the system attempts to initialize certain hardware interrupts, leading to an invalid operation where the system tries to 'sleep' while in a context that forbids it. This primarily affects the reliability and availability of devices using this specific hardware controller under real-time workloads.
Technical details
The vulnerability is a 'sleeping function called from invalid context' bug within the `gpio-eic-sprd.c` driver. In PREEMPT_RT kernels, standard `spinlock_t` structures are converted into sleeping mutexes. The `sprd_eic_irq_unmask()` function calls `sprd_eic_update()`, which acquires `sprd_eic->lock` using `spin_lock_irqsave()`. Because this path is reached via `irq_startup()` during hardware interrupt setup—a non-sleepable context—the use of a sleeping lock triggers a kernel panic or BUG. The fix involves converting the controller's lock to a `raw_spinlock_t` to ensure it remains a true spinlock that does not sleep, which is safe as the critical section only performs MMIO register updates.
Affected products
- Linux Linux Kernel 25518e024e3a to 96612bf2712cd961dbd9b52f3a9b4ab668f57628
Timeline
- 2026-06-17: disclosed: Initial patch submission by Runyu Xiao
- 2026-07-24: patched: Patch committed to stable tree by Greg Kroah-Hartman
- 2026-07-25: advisory: CVE-2026-64429 published
References
- https://git.kernel.org/stable/c/19d63fd528719ce7d06d9aeb88d25b7d6478198a
- https://git.kernel.org/stable/c/4750909a40da9016185e0ac991510a278cecb1e7
- https://git.kernel.org/stable/c/581ac2ad001ff1128931191f249a7f2074672b7a
- https://git.kernel.org/stable/c/5c3c9ec1172a4c3384b8b800b3a8896cc2c1b20e
- https://git.kernel.org/stable/c/6112fba4150039ccd90e29f2d1b788c73ad7b3dd
- https://git.kernel.org/stable/c/90f0109019e6817eb40a486671b7722d1544ae29
- https://git.kernel.org/stable/c/96612bf2712cd961dbd9b52f3a9b4ab668f57628