Description

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.

Weaknesses 1

Affected Products 8

References 2

• git.kernel.org https://git.kernel.org/stable/c/b0d7f5f0c9f05f1b6d4ee7110f15bef9c11f9df0
  Patch
• git.kernel.org https://git.kernel.org/stable/c/b1f8285bc8e3508c1fde23b5205f1270215d4984
  Patch

Remediation

• git.kernel.org https://git.kernel.org/stable/c/b0d7f5f0c9f05f1b6d4ee7110f15bef9c11f9df0
  Patch
• git.kernel.org https://git.kernel.org/stable/c/b1f8285bc8e3508c1fde23b5205f1270215d4984
  Patch