CVE-2023-53694

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

riscv: ftrace: Fixup panic by disabling preemption

In RISCV, we must use an AUIPC + JALR pair to encode an immediate, forming a jump that jumps to an address over 4K. This may cause errors if we want to enable kernel preemption and remove dependency from patching code with stop_machine(). For example, if a task was switched out on auipc. And, if we changed the ftrace function before it was switched back, then it would jump to an address that has updated 11:0 bits mixing with previous XLEN:12 part.

p: patched area performed by dynamic ftrace ftrace_prologue: p| REG_S ra, -SZREG(sp) p| auipc ra, 0x? ------------> preempted ... change ftrace function ... p| jalr -?(ra) <------------- switched back p| REG_L ra, -SZREG(sp) func: xxx ret

This patch fixes a potential kernel panic on RISC-V systems using ftrace with kernel preemption enabled. Because the RISC-V AUIPC + JALR instruction pair can be interrupted mid-patch, task preemption between these instructions could cause an incorrect jump address when tracing functions, leading to a crash. The issue does not permit privilege escalation or code execution — it’s a stability-only bug.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.