| From 9abc74a22d85ab29cef9896a2582a530da7e79bf Mon Sep 17 00:00:00 2001 |
| From: Richard Weinberger <richard@nod.at> |
| Date: Sat, 1 Apr 2017 00:41:57 +0200 |
| Subject: [PATCH] um: Fix PTRACE_POKEUSER on x86_64 |
| |
| 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. |
| |
| Cc: <stable@vger.kernel.org> |
| Reported-by: jie cao <cj3054@gmail.com> |
| Signed-off-by: Richard Weinberger <richard@nod.at> |
| |
| diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c |
| index a5c9910d234f..09a085bde0d4 100644 |
| --- 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, long addr, long data) |
| 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; |
| -- |
| 2.12.0 |
| |
