avoid spurious POLLIN returns in signalfd
The new code in kernel/signal.c does not allow fetching private signals
from another task. This patch avoid spurious POLLIN returns from a
signalfd poll(2) operation.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/signalfd.c b/fs/signalfd.c
index f1da892..3b07f26 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -133,7 +133,8 @@
* the peer disconnects.
*/
if (signalfd_lock(ctx, &lk)) {
- if (next_signal(&lk.tsk->pending, &ctx->sigmask) > 0 ||
+ if ((lk.tsk == current &&
+ next_signal(&lk.tsk->pending, &ctx->sigmask) > 0) ||
next_signal(&lk.tsk->signal->shared_pending,
&ctx->sigmask) > 0)
events |= POLLIN;