Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b74d0deb968e1f85942f17080eace015ce3c332c
Commit: b74d0deb968e1f85942f17080eace015ce3c332c
Parent: 8381e04b90ce9e7669a2d20aa7aaff3be910e447
Author: Roland McGrath <[EMAIL PROTECTED]>
AuthorDate: Wed Jun 6 03:59:00 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Jun 7 08:52:15 2007 -0700
Restrict clearing TIF_SIGPENDING
This patch should get a few birds. It prevents sigaction calls from
clearing TIF_SIGPENDING in other threads, which could leak -ERESTART*.
And It fixes ptrace_stop not to clear it, which done at the syscall exit
stop could leak -ERESTART*. It probably removes the harm from signalfd,
at least assuming it never calls dequeue_signal on kernel threads that
might have used block_all_signals.
Signed-off-by: Roland McGrath <[EMAIL PROTECTED]>
Cc: Andrew Morton <[EMAIL PROTECTED]>
Cc: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
Cc: Paul Mackerras <[EMAIL PROTECTED]>
Cc: Satoru Takeuchi <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
kernel/signal.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index acdfc05..fe590e0 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -105,7 +105,11 @@ static int recalc_sigpending_tsk(struct task_struct *t)
set_tsk_thread_flag(t, TIF_SIGPENDING);
return 1;
}
- clear_tsk_thread_flag(t, TIF_SIGPENDING);
+ /*
+ * We must never clear the flag in another thread, or in current
+ * when it's possible the current syscall is returning -ERESTART*.
+ * So we don't clear it here, and only callers who know they should do.
+ */
return 0;
}
@@ -121,7 +125,9 @@ void recalc_sigpending_and_wake(struct task_struct *t)
void recalc_sigpending(void)
{
- recalc_sigpending_tsk(current);
+ if (!recalc_sigpending_tsk(current))
+ clear_thread_flag(TIF_SIGPENDING);
+
}
/* Given the mask, find the first available signal that should be serviced. */
@@ -385,7 +391,8 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask,
siginfo_t *info)
}
}
}
- recalc_sigpending_tsk(tsk);
+ if (likely(tsk == current))
+ recalc_sigpending();
if (signr && unlikely(sig_kernel_stop(signr))) {
/*
* Set a marker that we have dequeued a stop signal. Our
@@ -1580,8 +1587,9 @@ static void ptrace_stop(int exit_code, int nostop_code,
siginfo_t *info)
/*
* Queued signals ignored us while we were stopped for tracing.
* So check for any that we should take before resuming user mode.
+ * This sets TIF_SIGPENDING, but never clears it.
*/
- recalc_sigpending();
+ recalc_sigpending_tsk(current);
}
void ptrace_notify(int exit_code)
-
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