From: Eric W. Biederman ebiederm@xmission.com
commit c200e4bb44e80b343c09841e7caaaca0aac5e5fa upstream.
User mode linux is the last user of the PT_DTRACE flag. Using the flag to indicate single stepping is a little confusing and worse changing tsk->ptrace without locking could potentionally cause problems.
So use a thread info flag with a better name instead of flag in tsk->ptrace.
Remove the definition PT_DTRACE as uml is the last user.
Cc: stable@vger.kernel.org Acked-by: Johannes Berg johannes@sipsolutions.net Tested-by: Kees Cook keescook@chromium.org Reviewed-by: Oleg Nesterov oleg@redhat.com Link: https://lkml.kernel.org/r/20220505182645.497868-3-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/um/include/asm/thread_info.h | 2 ++ arch/um/kernel/exec.c | 2 +- arch/um/kernel/process.c | 2 +- arch/um/kernel/ptrace.c | 8 ++++---- arch/um/kernel/signal.c | 4 ++-- include/linux/ptrace.h | 1 - 6 files changed, 10 insertions(+), 9 deletions(-)
--- a/arch/um/include/asm/thread_info.h +++ b/arch/um/include/asm/thread_info.h @@ -63,6 +63,7 @@ static inline struct thread_info *curren #define TIF_RESTORE_SIGMASK 7 #define TIF_NOTIFY_RESUME 8 #define TIF_SECCOMP 9 /* secure computing */ +#define TIF_SINGLESTEP 10 /* single stepping userspace */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) @@ -70,5 +71,6 @@ static inline struct thread_info *curren #define _TIF_MEMDIE (1 << TIF_MEMDIE) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1 << TIF_SECCOMP) +#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
#endif --- a/arch/um/kernel/exec.c +++ b/arch/um/kernel/exec.c @@ -44,7 +44,7 @@ void start_thread(struct pt_regs *regs, { PT_REGS_IP(regs) = eip; PT_REGS_SP(regs) = esp; - current->ptrace &= ~PT_DTRACE; + clear_thread_flag(TIF_SINGLESTEP); #ifdef SUBARCH_EXECVE1 SUBARCH_EXECVE1(regs->regs); #endif --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -380,7 +380,7 @@ int singlestepping(void * t) { struct task_struct *task = t ? t : current;
- if (!(task->ptrace & PT_DTRACE)) + if (!test_thread_flag(TIF_SINGLESTEP)) return 0;
if (task->thread.singlestep_syscall) --- a/arch/um/kernel/ptrace.c +++ b/arch/um/kernel/ptrace.c @@ -12,7 +12,7 @@
void user_enable_single_step(struct task_struct *child) { - child->ptrace |= PT_DTRACE; + set_tsk_thread_flag(child, TIF_SINGLESTEP); child->thread.singlestep_syscall = 0;
#ifdef SUBARCH_SET_SINGLESTEPPING @@ -22,7 +22,7 @@ void user_enable_single_step(struct task
void user_disable_single_step(struct task_struct *child) { - child->ptrace &= ~PT_DTRACE; + clear_tsk_thread_flag(child, TIF_SINGLESTEP); child->thread.singlestep_syscall = 0;
#ifdef SUBARCH_SET_SINGLESTEPPING @@ -121,7 +121,7 @@ static void send_sigtrap(struct uml_pt_r }
/* - * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and + * XXX Check TIF_SINGLESTEP for singlestepping check and * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check */ int syscall_trace_enter(struct pt_regs *regs) @@ -145,7 +145,7 @@ void syscall_trace_leave(struct pt_regs audit_syscall_exit(regs);
/* Fake a debug trap */ - if (ptraced & PT_DTRACE) + if (test_thread_flag(TIF_SINGLESTEP)) send_sigtrap(®s->regs, 0);
if (!test_thread_flag(TIF_SYSCALL_TRACE)) --- a/arch/um/kernel/signal.c +++ b/arch/um/kernel/signal.c @@ -53,7 +53,7 @@ static void handle_signal(struct ksignal unsigned long sp; int err;
- if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED)) + if (test_thread_flag(TIF_SINGLESTEP) && (current->ptrace & PT_PTRACED)) singlestep = 1;
/* Did we come from a system call? */ @@ -128,7 +128,7 @@ void do_signal(struct pt_regs *regs) * on the host. The tracing thread will check this flag and * PTRACE_SYSCALL if necessary. */ - if (current->ptrace & PT_DTRACE) + if (test_thread_flag(TIF_SINGLESTEP)) current->thread.singlestep_syscall = is_syscall(PT_REGS_IP(¤t->thread.regs));
--- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -30,7 +30,6 @@ extern int ptrace_access_vm(struct task_
#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */ #define PT_PTRACED 0x00000001 -#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
#define PT_OPT_FLAG_SHIFT 3 /* PT_TRACE_* event enable flags */