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ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK

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There are a few system calls (pselect, ppoll, etc) which replace a task
sigmask while they are running in a kernel-space

When a task calls one of these syscalls, the kernel saves a current
sigmask in task->saved_sigmask and sets a syscall sigmask.

On syscall-exit-stop, ptrace traps a task before restoring the
saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and
PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by
saved_sigmask, when the task returns to user-space.

This patch fixes this problem.  PTRACE_GETSIGMASK returns saved_sigmask
if it's set.  PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag.

Link: http://lkml.kernel.org/r/20181120060616.6043-1-avagin@gmail.com
Fixes: 29000caecb ("ptrace: add ability to get/set signal-blocked mask")
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrei Vagin 2019-03-28 20:44:13 -07:00 • committed by Linus Torvalds
parent eebf364806
commit fcfc2aa018
2 changed files with 31 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

18
include/linux/sched/signal.h
View file

@ -418,10 +418,20 @@ static inline void set_restore_sigmask(void)
set_thread_flag(TIF_RESTORE_SIGMASK);
WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
{
clear_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
}
static inline void clear_restore_sigmask(void)
{
clear_thread_flag(TIF_RESTORE_SIGMASK);
}
static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
{
return test_tsk_thread_flag(tsk, TIF_RESTORE_SIGMASK);
}
static inline bool test_restore_sigmask(void)
{
return test_thread_flag(TIF_RESTORE_SIGMASK);
@ -439,6 +449,10 @@ static inline void set_restore_sigmask(void)
current->restore_sigmask = true;
WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_tsk_restore_sigmask(struct task_struct *tsk)
{
tsk->restore_sigmask = false;
}
static inline void clear_restore_sigmask(void)
{
current->restore_sigmask = false;
@ -447,6 +461,10 @@ static inline bool test_restore_sigmask(void)
{
return current->restore_sigmask;
}
static inline bool test_tsk_restore_sigmask(struct task_struct *tsk)
{
return tsk->restore_sigmask;
}
static inline bool test_and_clear_restore_sigmask(void)
{
if (!current->restore_sigmask)