Re: [PATCH] riscv: ptrace: reject CFI regset access when extensions are absent

[Paul Walmsley]

On Thu, 20 Aug 2026, Chen Pei wrote:

> riscv_cfi_get() and riscv_cfi_set() do not check whether the Zicfilp
> or Zicfiss extensions are present. On systems without them,
> PTRACE_GETREGSET on REGSET_CFI still succeeds and returns a zeroed
> user_cfi_state, misleading debuggers into believing the register set
> is available, and PTRACE_SETREGSET silently accepts writes that have
> no effect (e.g. clearing SR_ELP).
> 
> Reject the access with -EINVAL when neither branch landing pads nor
> shadow stack is available to userspace, using the same availability
> helpers as the prctl path.
> 
> Fixes: 2af7c9cf021c ("riscv/ptrace: expose riscv CFI status and state via ptrace and in core files")
> Signed-off-by: Chen Pei <cp0613@xxxxxxxxxxxxxxxxx>

Thanks, queued for v7.3-rc.


- Paul