From: Michael Neuling Date: Fri, 1 May 2026 06:23:20 +0000 (+0000) Subject: riscv: Fix register corruption from uninitialized cregs on error X-Git-Tag: v7.1-rc4~8^2~5 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6ebcbb53fc9bc30843054ed99fd60b8e542628f4;p=thirdparty%2Flinux.git riscv: Fix register corruption from uninitialized cregs on error compat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when user_regset_copyin() fails. Since cregs is an uninitialized stack variable, a copyin failure causes uninitialized stack data to be written into the target task's pt_regs, corrupting its register state and potentially leaking kernel stack contents. compat_restore_sigcontext() has the same issue: it calls cregs_to_regs() even when __copy_from_user() fails, leading to the same corruption of the signal-returning task's register state on error. Only call cregs_to_regs() when the user copy succeeds. Fixes: 4608c159594f ("riscv: compat: ptrace: Add compat_arch_ptrace implement") Fixes: 7383ee05314b ("riscv: compat: signal: Add rt_frame implementation") Signed-off-by: Michael Neuling Assisted-by: Cursor:claude-4.6-opus-high-thinking Link: https://patch.msgid.link/20260501062320.2339562-1-mikey@neuling.org Signed-off-by: Paul Walmsley --- diff --git a/arch/riscv/kernel/compat_signal.c b/arch/riscv/kernel/compat_signal.c index 6ec4e34255a9..cf3eb33a11e4 100644 --- a/arch/riscv/kernel/compat_signal.c +++ b/arch/riscv/kernel/compat_signal.c @@ -107,6 +107,8 @@ static long compat_restore_sigcontext(struct pt_regs *regs, /* sc_regs is structured the same as the start of pt_regs */ err = __copy_from_user(&cregs, &sc->sc_regs, sizeof(sc->sc_regs)); + if (unlikely(err)) + return err; cregs_to_regs(&cregs, regs); diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index 93de2e7a3074..793bcee46182 100644 --- a/arch/riscv/kernel/ptrace.c +++ b/arch/riscv/kernel/ptrace.c @@ -577,8 +577,8 @@ static int compat_riscv_gpr_set(struct task_struct *target, struct compat_user_regs_struct cregs; ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &cregs, 0, -1); - - cregs_to_regs(&cregs, task_pt_regs(target)); + if (!ret) + cregs_to_regs(&cregs, task_pt_regs(target)); return ret; }