The patch titled
ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm
has been added to the -mm tree. Its filename is
ptrace-ptrace_getfdpic-fix-the-unsafe-usage-of-child-mm.patch
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------------------------------------------------------
Subject: ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Now that Mike Frysinger unified the FDPIC ptrace code, we can fix the
unsafe usage of child->mm in ptrace_request(PTRACE_GETFDPIC).
We have the reference to task_struct, and ptrace_check_attach() verified
the tracee is stopped. But nothing can protect from SIGKILL after that,
we must not assume child->mm != NULL.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Mike Frysinger <vapier.adi@xxxxxxxxx>
Acked-by: David Howells <dhowells@xxxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxxx>
Acked-by: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/ptrace.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff -puN kernel/ptrace.c~ptrace-ptrace_getfdpic-fix-the-unsafe-usage-of-child-mm kernel/ptrace.c
--- a/kernel/ptrace.c~ptrace-ptrace_getfdpic-fix-the-unsafe-usage-of-child-mm
+++ a/kernel/ptrace.c
@@ -596,18 +596,24 @@ int ptrace_request(struct task_struct *c
#ifdef CONFIG_BINFMT_ELF_FDPIC
case PTRACE_GETFDPIC: {
+ struct mm_struct *mm = get_task_mm(child);
unsigned long tmp = 0;
+ ret = -ESRCH;
+ if (!mm)
+ break;
+
switch (addr) {
case PTRACE_GETFDPIC_EXEC:
- tmp = child->mm->context.exec_fdpic_loadmap;
+ tmp = mm->context.exec_fdpic_loadmap;
break;
case PTRACE_GETFDPIC_INTERP:
- tmp = child->mm->context.interp_fdpic_loadmap;
+ tmp = mm->context.interp_fdpic_loadmap;
break;
default:
break;
}
+ mmput(mm);
ret = put_user(tmp, (unsigned long __user *) data);
break;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
fix-stop_machine-reimplement-using-cpu_stop.patch
ptrace-unify-fdpic-implementations.patch
ptrace-ptrace_getfdpic-fix-the-unsafe-usage-of-child-mm.patch
signals-check_kill_permission-dont-check-creds-if-same_thread_group.patch
kmod-add-init-function-to-usermodehelper.patch
exec-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch
umh-creds-convert-call_usermodehelper_keys-to-use-subprocess_info-init.patch
umh-creds-kill-subprocess_info-cred-logic.patch
call_usermodehelper-no-need-to-unblock-signals.patch
wait_for_helper-sigchld-from-user-space-can-lead-to-use-after-free.patch
call_usermodehelper-simplify-fix-umh_no_wait-case.patch
call_usermodehelper-umh_wait_exec-ignores-kernel_thread-failure.patch
coredump-factor-out-the-not-ispipe-file-checks.patch
coredump-cleanup-ispipe-code.patch
coredump-factor-out-put_cred-calls.patch
coredump-shift-down_writemmap_sem-into-coredump_wait.patch
exit-exit_notify-can-trust-signal-notify_count-0.patch
exit-change-zap_other_threads-to-count-sub-threads.patch
exit-avoid-sig-count-in-de_thread-__exit_signal-synchronization.patch
exit-avoid-sig-count-in-__exit_signal-to-detect-the-group-dead-case.patch
posix-cpu-timers-avoid-task-signal-=-null-checks.patch
ia64-ptrace_attach_sync_user_rbs-avoid-task-signal-=-null-checks.patch
fork-exit-move-tty_kref_put-outside-of-__cleanup_signal.patch
signals-make-task_struct-signal-immutable-refcountable.patch
signals-clear-signal-tty-when-the-last-thread-exits.patch
signals-clear-signal-tty-when-the-last-thread-exits-fix.patch
signals-kill-the-awful-task_rq_unlock_wait-hack.patch
exit-__exit_signal-use-thread_group_leader-consistently.patch
kill-the-obsolete-thread_group_cputime_free-and-taskstats_tgid_init-helpers.patch
exit-move-taskstats_tgid_free-from-__exit_signal-to-free_signal_struct.patch
check_unshare_flags-kill-the-bogus-clone_sighand-sig-count-check.patch
proc-get_nr_threads-doesnt-need-siglock-any-longer.patch
proc_sched_show_task-use-get_nr_threads.patch
keyctl_session_to_parent-use-thread_group_empty-to-check-singlethreadness.patch
proc-turn-signal_struct-count-into-int-nr_threads.patch
proc-turn-signal_struct-count-into-int-nr_threads-checkpatch-fixes.patch
proc-cleanup-remove-unused-assignments.patch
init_task-should-initialize-thread_group-list.patch
pids-init_struct_pidtasks-should-never-see-the-swapper-process.patch
pids-fix-fork_idle-to-setup-pids-correctly.patch
init_sighand-use-sig_dfl-instead-of-null.patch
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