From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, jie cao , Richard Weinberger Subject: [PATCH 4.11 026/114] um: Fix PTRACE_POKEUSER on x86_64 Date: Thu, 18 May 2017 12:45:36 +0200 Message-Id: <20170518103608.733928567@linuxfoundation.org> In-Reply-To: <20170518103604.736737251@linuxfoundation.org> References: <20170518103604.736737251@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Richard Weinberger commit 9abc74a22d85ab29cef9896a2582a530da7e79bf upstream. This is broken since ever but sadly nobody noticed. Recent versions of GDB set DR_CONTROL unconditionally and UML dies due to a heap corruption. It turns out that the PTRACE_POKEUSER was copy&pasted from i386 and assumes that addresses are 4 bytes long. Fix that by using 8 as address size in the calculation. Reported-by: jie cao Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman --- arch/x86/um/ptrace_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/um/ptrace_64.c +++ b/arch/x86/um/ptrace_64.c @@ -125,7 +125,7 @@ int poke_user(struct task_struct *child, else if ((addr >= offsetof(struct user, u_debugreg[0])) && (addr <= offsetof(struct user, u_debugreg[7]))) { addr -= offsetof(struct user, u_debugreg[0]); - addr = addr >> 2; + addr = addr >> 3; if ((addr == 4) || (addr == 5)) return -EIO; child->thread.arch.debugregs[addr] = data;