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Thu, 09 Apr 2026 02:12:06 -0700 (PDT) Sender: Michael Neuling From: Michael Neuling To: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , "Mike Rapoport (Microsoft)" , "Vishal Moola (Oracle)" , Albert Ou , Aleksa Paunovic , Aleksandar Rikalo , Alexandre Ghiti , Andrew Jones , Andrew Morton , Arnd Bergmann , David Hildenbrand , Djordje Todorovic , Guo Ren , Junhui Liu , Kevin Brodsky , Lorenzo Stoakes , Nam Cao , Oleg Nesterov , Oscar Salvador , Palmer Dabbelt , Paul Walmsley , Qinglin Pan , Raj Vishwanathan4 , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Cc: Michael Neuling Subject: [PATCH 2/5] riscv: ptrace: Fix register corruption in compat_riscv_gpr_set on error Date: Thu, 9 Apr 2026 09:11:40 +0000 Message-ID: <20260409091143.1348853-3-mikey@neuling.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260409091143.1348853-1-mikey@neuling.org> References: <20260409091143.1348853-1-mikey@neuling.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Only call cregs_to_regs() when user_regset_copyin() succeeds. Fixes: 4608c15959 ("riscv: compat: ptrace: Add compat_arch_ptrace implement") Signed-off-by: Michael Neuling Assisted-by: Cursor:claude-4.6-opus-high-thinking --- arch/riscv/kernel/ptrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c index 93de2e7a30..793bcee461 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; } -- 2.43.0