aboutsummaryrefslogtreecommitdiff
path: root/kernel/ptrace.c
diff options
context:
space:
mode:
authorOleg Nesterov <oleg@redhat.com>2009-06-17 16:27:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:03:51 -0700
commitb79b7ba93df14a1fc0b8d4d6d78a0e097de03bbd (patch)
tree65ce7c7335fc1dd0a91a3224466c4eaa0ec489f4 /kernel/ptrace.c
parent5cb11446892833e50970fb2277a9f7563b0a8bd3 (diff)
downloadlinux-2.6.34-ux500-b79b7ba93df14a1fc0b8d4d6d78a0e097de03bbd.tar.gz
ptrace: ptrace_attach: check PF_KTHREAD + exit_state instead of ->mm
- Add PF_KTHREAD check to prevent attaching to the kernel thread with a borrowed ->mm. With or without this change we can race with daemonize() which can set PF_KTHREAD or clear ->mm after ptrace_attach() does the check, but this doesn't matter because reparent_to_kthreadd() does ptrace_unlink(). - Kill "!task->mm" check. We don't really care about ->mm != NULL, and the task can call exit_mm() right after we drop task_lock(). What we need is to make sure we can't attach after exit_notify(), check task->exit_state != 0 instead. Also, move the "already traced" check down for cosmetic reasons. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Acked-by: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r--kernel/ptrace.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index f6d8b8cb5e3..9439bd3331a 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -172,6 +172,8 @@ int ptrace_attach(struct task_struct *task)
audit_ptrace(task);
retval = -EPERM;
+ if (unlikely(task->flags & PF_KTHREAD))
+ goto out;
if (same_thread_group(task, current))
goto out;
@@ -182,8 +184,6 @@ int ptrace_attach(struct task_struct *task)
retval = mutex_lock_interruptible(&task->cred_guard_mutex);
if (retval < 0)
goto out;
-
- retval = -EPERM;
repeat:
/*
* Nasty, nasty.
@@ -203,23 +203,24 @@ repeat:
goto repeat;
}
- if (!task->mm)
- goto bad;
- /* the same process cannot be attached many times */
- if (task->ptrace & PT_PTRACED)
- goto bad;
retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
if (retval)
goto bad;
- /* Go */
+ retval = -EPERM;
+ if (unlikely(task->exit_state))
+ goto bad;
+ if (task->ptrace & PT_PTRACED)
+ goto bad;
+
task->ptrace |= PT_PTRACED;
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
__ptrace_link(task, current);
-
send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+ retval = 0;
bad:
write_unlock_irqrestore(&tasklist_lock, flags);
task_unlock(task);