diff options
| -rw-r--r-- | arch/x86/entry/common.c | 6 | ||||
| -rw-r--r-- | arch/x86/include/asm/syscall.h | 5 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 15 | ||||
| -rw-r--r-- | arch/x86/kernel/signal.c | 26 |
5 files changed, 42 insertions, 13 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 9e1e27d31c6d..be8c403f8117 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -270,8 +270,12 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) * handling, because syscall restart has a fixup for compat * syscalls. The fixup is exercised by the ptrace_syscall_32 * selftest. + * + * We also need to clear TS_REGS_POKED_I386: the 32-bit tracer + * special case only applies after poking regs and before the + * very next return to user mode. */ - ti->status &= ~TS_COMPAT; + ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); #endif user_enter_irqoff(); diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h index 999b7cd2e78c..4e23dd15c661 100644 --- a/arch/x86/include/asm/syscall.h +++ b/arch/x86/include/asm/syscall.h @@ -60,7 +60,7 @@ static inline long syscall_get_error(struct task_struct *task, * TS_COMPAT is set for 32-bit syscall entries and then * remains set until we return to user mode. */ - if (task_thread_info(task)->status & TS_COMPAT) + if (task_thread_info(task)->status & (TS_COMPAT|TS_I386_REGS_POKED)) /* * Sign-extend the value so (int)-EFOO becomes (long)-EFOO * and will match correctly in comparisons. @@ -239,9 +239,6 @@ static inline int syscall_get_arch(void) * TS_COMPAT is set for 32-bit syscall entry and then * remains set until we return to user mode. * - * TIF_IA32 tasks should always have TS_COMPAT set at - * system call time. - * * x32 tasks should be considered AUDIT_ARCH_X86_64. */ if (task_thread_info(current)->status & TS_COMPAT) diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 89bff044a6f5..f856c590c309 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -219,6 +219,9 @@ static inline unsigned long current_stack_pointer(void) * have to worry about atomic accesses. */ #define TS_COMPAT 0x0002 /* 32bit syscall active (64BIT)*/ +#ifdef CONFIG_COMPAT +#define TS_I386_REGS_POKED 0x0004 /* regs poked by 32-bit ptracer */ +#endif #define TS_RESTORE_SIGMASK 0x0008 /* restore signal mask in do_signal() */ #ifndef __ASSEMBLY__ diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 600edd225e81..f79576a541ff 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -923,15 +923,18 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 value) case offsetof(struct user32, regs.orig_eax): /* - * A 32-bit debugger setting orig_eax means to restore - * the state of the task restarting a 32-bit syscall. - * Make sure we interpret the -ERESTART* codes correctly - * in case the task is not actually still sitting at the - * exit from a 32-bit syscall with TS_COMPAT still set. + * Warning: bizarre corner case fixup here. A 32-bit + * debugger setting orig_eax to -1 wants to disable + * syscall restart. Make sure that the syscall + * restart code sign-extends orig_ax. Also make sure + * we interpret the -ERESTART* codes correctly if + * loaded into regs->ax in case the task is not + * actually still sitting at the exit from a 32-bit + * syscall with TS_COMPAT still set. */ regs->orig_ax = value; if (syscall_get_nr(child, regs) >= 0) - task_thread_info(child)->status |= TS_COMPAT; + task_thread_info(child)->status |= TS_I386_REGS_POKED; break; case offsetof(struct user32, regs.eflags): diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 22cc2f9f8aec..9747a6358949 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -760,8 +760,30 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs) static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs) { -#ifdef CONFIG_X86_64 - if (in_ia32_syscall()) + /* + * This function is fundamentally broken as currently + * implemented. + * + * The idea is that we want to trigger a call to the + * restart_block() syscall and that we want in_ia32_syscall(), + * in_x32_syscall(), etc. to match whatever they were in the + * syscall being restarted. We assume that the syscall + * instruction at (regs->ip - 2) matches whatever syscall + * instruction we used to enter in the first place. + * + * The problem is that we can get here when ptrace pokes + * syscall-like values into regs even if we're not in a syscall + * at all. + * + * For now, we maintain historical behavior and guess based on + * stored state. We could do better by saving the actual + * syscall arch in restart_block or (with caveats on x32) by + * checking if regs->ip points to 'int $0x80'. The current + * behavior is incorrect if a tracer has a different bitness + * than the tracee. + */ +#ifdef CONFIG_IA32_EMULATION + if (current_thread_info()->status & (TS_COMPAT|TS_I386_REGS_POKED)) return __NR_ia32_restart_syscall; #endif #ifdef CONFIG_X86_X32_ABI |