riscv: trace: fix snapshot deadlock with sbi ecall
Summary
riscv: trace: fix snapshot deadlock with sbi ecall
Original description
The description as published by the source.
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.
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-23217 linux-lts
- Debian DEBIAN-CVE-2026-23217 linux
- Ubuntu UBUNTU-CVE-2026-23217 linux
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org