From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E2C1321F5F for ; Sun, 28 Jun 2026 19:18:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782674319; cv=none; b=uCD+F9j7TPQNjGxBps/6F3SkQZPrhgUSf1ym/i1PkztRt8s1Mb4pz3+V7INr/OHsHlzQ0X4qLuEpQv1nMrvsHsQi+VpZCXKNDpQXmjMm6ZuPpd/8spP7QOevpiT85SvmfQbsc6f6LK9FTFSLTSDEDCUIElg3gbTikKug66sTaik= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782674319; c=relaxed/simple; bh=gLOyjyTBIPtvYWp79oq5MrNSJcJvZKzzL67jqkYL7vE=; h=Date:To:From:Subject:Message-Id; b=r1ErX/1FSV8v+s3ZeRJrsN0KEsGSg6QSbOOgGuv6tHuxYvurYdn0isb0bO8/vQRc9uw6M4XuQ+kDqtXlzAZKQPnhSN6mE1BNwXG7XvU+du7lhm0Aq9fFsyN69mfMW5JV6Eis0SrvZx5wSAckxwgdHSNDum0LBVC5XH5KYeCYyDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 584101F000E9; Sun, 28 Jun 2026 19:18:30 +0000 (UTC) Date: Sun, 28 Jun 2026 12:17:59 -0700 To: mm-commits@vger.kernel.org,include@grrlz.net,ebiederm@xmission.com,oleg@redhat.com,akpm@linux-foundation.org From: Andrew Morton Subject: + signal-change-sys_kill-to-use-send_sig_noinfo.patch added to mm-nonmm-unstable branch Message-Id: <20260628191830.584101F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: signal: change sys_kill() to use SEND_SIG_NOINFO has been added to the -mm mm-nonmm-unstable branch. Its filename is signal-change-sys_kill-to-use-send_sig_noinfo.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/signal-change-sys_kill-to-use-send_sig_noinfo.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Oleg Nesterov Subject: signal: change sys_kill() to use SEND_SIG_NOINFO Date: Fri, 26 Jun 2026 17:33:08 +0200 prepare_kill_siginfo(PIDTYPE_TGID) fills si_code = SI_USER and sets si_pid/si_uid in the sender's namespace. Then send_signal_locked() translates si_pid/si_uid to the target's namespace. SEND_SIG_NOINFO exists precisely for the case when si_code == SI_USER and si_pid/si_uid are the sender's ids; this is exactly what sys_kill() does via prepare_kill_siginfo(PIDTYPE_TGID). Change sys_kill() to use it directly. SEND_SIG_NOINFO produces the same result: si_code = SI_USER, and __send_signal_locked() computes si_pid/si_uid directly in the target's namespace. The force computation is also the same: both check if the sender is visible in the target's pid namespace. This is just a cleanup and microoptimization (especially with [1]), this skips the has_si_pid_and_uid() block in send_signal_locked() and offloads the namespace translation logic to __send_signal_locked(SEND_SIG_NOINFO) which uses the simpler computations. NOTE: As a "side effect" this also fixes the kill(pid < 0, sig) case where send_signal_locked() rewrites si_pid/si_uid in the shared siginfo, corrupting it for subsequent recipients. But for other group senders like __kill_pgrp_info() we still need the fix from Bradley Morgan [1] who found this problem. TODO: kill prepare_kill_siginfo() and change other users to use SEND_SIG_NOINFO too. This needs trivial changes in __send_signal_locked() and TP_STORE_SIGINFO(). Link: https://lore.kernel.org/aj6btAZqYuv59a8w@redhat.com Link: https://lore.kernel.org/all/20260622164029.11474-1-include@grrlz.net/ [1] Signed-off-by: Oleg Nesterov Reviewed-by: Bradley Morgan Cc: Eric Biederman Signed-off-by: Andrew Morton --- kernel/signal.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) --- a/kernel/signal.c~signal-change-sys_kill-to-use-send_sig_noinfo +++ a/kernel/signal.c @@ -3954,11 +3954,7 @@ static void prepare_kill_siginfo(int sig */ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) { - struct kernel_siginfo info; - - prepare_kill_siginfo(sig, &info, PIDTYPE_TGID); - - return kill_something_info(sig, &info, pid); + return kill_something_info(sig, SEND_SIG_NOINFO, pid); } /* _ Patches currently in -mm which might be from oleg@redhat.com are signal-change-sys_kill-to-use-send_sig_noinfo.patch