From c58b2c46505568ac70aadffc338a7a90272c6d4b Mon Sep 17 00:00:00 2001 From: Richard Weinberger 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. Reported-by: jie cao Signed-off-by: Richard Weinberger Signed-off-by: Ben Hutchings --- arch/x86/um/ptrace_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c index 3b52bf0b418a..b0d25e6ef464 100644 --- a/arch/x86/um/ptrace_64.c +++ b/arch/x86/um/ptrace_64.c @@ -120,7 +120,7 @@ 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; -- 2.39.2