CVE-2026-23217

In the Linux kernel, the following vulnerability has been resolved:

riscv: trace: fix snapshot deadlock with sbi ecall

If sbi_ecall.c's functions are traceable,

echo "__sbi_ecall:snapshot" > /sys/kernel/tracing/set_ftrace_filter

may get the kernel into a deadlock.

(Functions in sbi_ecall.c are excluded from tracing if

CONFIG_RISCV_ALTERNATIVE_EARLY is set.)

__sbi_ecall triggers a snapshot of the ringbuffer. The snapshot code

raises an IPI interrupt, which results in another call to __sbi_ecall

and another snapshot...

All it takes to get into this endless loop is one initial __sbi_ecall.

On RISC-V systems without SSTC extension, the clock events in

timer-riscv.c issue periodic sbi ecalls, making the problem easy to

trigger.

Always exclude the sbi_ecall.c functions from tracing to fix the

potential deadlock.

sbi ecalls can easiliy be logged via trace events, excluding ecall

functions from function tracing is not a big limitation.