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From: "Eric W. Biederman" <ebiederm@xmission.com>
To: linux-kernel@vger.kernel.org
Cc: Oleg Nesterov <oleg@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-api@vger.kernel.org,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 08/10] signal: Never allocate siginfo for SIGKILL or SIGSTOP
Date: Mon,  3 Sep 2018 22:44:28 +0200	[thread overview]
Message-ID: <20180903204430.25473-8-ebiederm@xmission.com> (raw)
In-Reply-To: <87musyl3fa.fsf@xmission.com>

The SIGKILL and SIGSTOP signals are never delivered to userspace so
queued siginfo for these signals can never be observed.  Therefore
remove the chance of failure by never even attempting to allocate
siginfo in those cases.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/signal.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 20931a892ace..d7d1adf735f4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1054,10 +1054,11 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 
 	result = TRACE_SIGNAL_DELIVERED;
 	/*
-	 * fast-pathed signals for kernel-internal things like SIGSTOP
-	 * or SIGKILL.
+	 * Skip useless siginfo allocation for SIGKILL SIGSTOP,
+	 * and kernel threads.
 	 */
-	if ((info == SEND_SIG_FORCED) || (t->flags & PF_KTHREAD))
+	if ((info == SEND_SIG_FORCED) ||
+	    sig_kernel_only(sig) || (t->flags & PF_KTHREAD))
 		goto out_set;
 
 	/*
-- 
2.17.1


  parent reply	other threads:[~2018-09-03 20:45 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-03 20:41 [PATCH 00/10] Removing SEND_SIG_FORCED Eric W. Biederman
2018-09-03 20:41 ` Eric W. Biederman
2018-09-03 20:44 ` [PATCH 01/10] signal: Always ignore SIGKILL and SIGSTOP sent to the global init Eric W. Biederman
2018-09-03 20:44 ` [PATCH 02/10] signal: Properly deliver SIGILL from uprobes Eric W. Biederman
2018-09-03 20:44 ` [PATCH 03/10] signal: Properly deliver SIGSEGV from x86 uprobes Eric W. Biederman
2018-09-03 20:44 ` [PATCH 04/10] signal: Always deliver the kernel's SIGKILL and SIGSTOP to a pid namespace init Eric W. Biederman
2018-09-03 20:44 ` [PATCH 05/10] signal: send_sig_all no longer needs SEND_SIG_FORCED Eric W. Biederman
2018-09-03 20:44 ` [PATCH 06/10] signal: Remove the siginfo paramater from kernel_dqueue_signal Eric W. Biederman
2018-09-03 20:44 ` [PATCH 07/10] signal: Don't send siginfo to kthreads Eric W. Biederman
2018-09-03 20:44 ` Eric W. Biederman [this message]
2018-09-03 20:44 ` [PATCH 09/10] signal: Use SEND_SIG_PRIV not SEND_SIG_FORCED with SIGKILL and SIGSTOP Eric W. Biederman
2018-09-03 20:44 ` [PATCH 10/10] signal: Remove SEND_SIG_FORCED Eric W. Biederman
2018-09-08 11:03 ` [PATCH 00/10] Removing SEND_SIG_FORCED Thomas Gleixner
2018-09-16 18:04 ` [PATCH 0/4] signal: Cleanups Eric W. Biederman
2018-09-16 18:04   ` [PATCH 1/4] tty_io: Use group_send_sig_info in __do_SACK to note it is a session being killed Eric W. Biederman
2018-09-16 18:05   ` [PATCH 2/4] signal: Use group_send_sig_info to kill all processes in a pid namespace Eric W. Biederman
2018-09-16 18:06   ` [PATCH 3/4] signal: Remove specific_send_sig_info Eric W. Biederman
2018-09-16 18:06   ` [PATCH 4/4] signal: Pair exports with their functions Eric W. Biederman

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