diff options
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 53 |
1 files changed, 20 insertions, 33 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 0649f166d7c6..98b0a2ccc33c 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -609,14 +609,6 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, int gen_len, gen_type; struct perf_event_attr attr; - /* - * We should have at least an inactive breakpoint at this - * slot. It means the user is writing dr7 without having - * written the address register first - */ - if (!bp) - return -EINVAL; - err = arch_bp_generic_fields(len, type, &gen_len, &gen_type); if (err) return err; @@ -634,52 +626,47 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type, */ static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data) { - struct thread_struct *thread = &(tsk->thread); + struct thread_struct *thread = &tsk->thread; unsigned long old_dr7; - int i, orig_ret = 0, rc = 0; - int second_pass = 0; + bool second_pass = false; + int i, rc, ret = 0; data &= ~DR_CONTROL_RESERVED; old_dr7 = ptrace_get_dr7(thread->ptrace_bps); + restore: - /* - * Loop through all the hardware breakpoints, making the - * appropriate changes to each. - */ + rc = 0; for (i = 0; i < HBP_NUM; i++) { unsigned len, type; bool disabled = !decode_dr7(data, i, &len, &type); struct perf_event *bp = thread->ptrace_bps[i]; - if (disabled) { + if (!bp) { + if (disabled) + continue; /* - * Don't unregister the breakpoints right-away, unless - * all register_user_hw_breakpoint() requests have - * succeeded. This prevents any window of opportunity - * for debug register grabbing by other users. + * We should have at least an inactive breakpoint at + * this slot. It means the user is writing dr7 without + * having written the address register first. */ - if (!bp || !second_pass) - continue; + rc = -EINVAL; + break; } rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled); if (rc) break; } - /* - * Make a second pass to free the remaining unused breakpoints - * or to restore the original breakpoints if an error occurred. - */ - if (!second_pass) { - second_pass = 1; - if (rc < 0) { - orig_ret = rc; - data = old_dr7; - } + + /* Restore if the first pass failed, second_pass shouldn't fail. */ + if (rc && !WARN_ON(second_pass)) { + ret = rc; + data = old_dr7; + second_pass = true; goto restore; } - return orig_ret < 0 ? orig_ret : rc; + return ret; } /* |