From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 886E43B5315 for ; Sat, 28 Feb 2026 17:52:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772301140; cv=none; b=sy3hGX7BSjbpvJswVX9GjciK9LymwBlTZlIIZtPRIJwzW2PlIcQXP78rc1UgYhQczNv0VSQTsOwRjv7kFZQE347DwXhKCaMarmXZDysfoHFy0Gt6SX0KiOK23dFk021v+xQpomv+8VIkB+A38lraUVJKuyXFaU7bl9/k/PETRbI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772301140; c=relaxed/simple; bh=+OCkzWvvZslLw7jixUYG+u0VUbpJMsjVT/+U6lvVJfc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RQzJsnDocGwrGIm4onmUYI7GSHILBcm95GCHUDEIvD37vQJyuoso7NEhnWqHazMckJcYqnDl8JwbbiJXENotSM6WsbaH1U50HivVOLZGOPWvaKN5YMUjrdcNGueGIL+MFksk2MbeCAdMDerXWj5EXroce2qj5RTPWda93iIjodU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ufoXQULB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ufoXQULB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3C44C2BC9E; Sat, 28 Feb 2026 17:52:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772301140; bh=+OCkzWvvZslLw7jixUYG+u0VUbpJMsjVT/+U6lvVJfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ufoXQULBiBzsS25PEIbKHgTmu+n9Qr/w5i9hDgDvgTI4+ClZXWj+1fvP7rLOnqR/K eGyVsLdybP8oIKWK8n/hidbvZWm4Gzcv138I2T6d2IiQ6Lpb9VAQQSFGAatwCIuDbM smq1RruIKurAp7nRdWLMzWBXdSBhHE8d/f5DvjfQbM7WHJmZaSSmQg8UbBYQ4hw3H4 bZdwLo+KuMdJlthajF2SsmHY3JimVCErPHqVEWZTFb3t5p2YOz9V6hFVwUufWpwQsA gdESOijoDjTpxR2lDlqu1VAywapeVB3WrREHrF1nUZ5SCnUyuYtT7AeyDbsnlcO5d1 I2BOhQnjpisRA== From: Sasha Levin To: patches@lists.linux.dev Cc: Tiwei Bie , Johannes Berg , Sasha Levin Subject: [PATCH 6.18 301/752] um: Preserve errno within signal handler Date: Sat, 28 Feb 2026 12:40:12 -0500 Message-ID: <20260228174750.1542406-301-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228174750.1542406-1-sashal@kernel.org> References: <20260228174750.1542406-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Tiwei Bie [ Upstream commit f68b2d5a907b53eed99cf2efcaaae116df73c298 ] We rely on errno to determine whether a syscall has failed, so we need to ensure that accessing errno is async-signal-safe. Currently, we preserve the errno in sig_handler_common(), but it doesn't cover every possible case. Let's do it in hard_handler() instead, which is the signal handler we actually register. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20260106001228.1531146-2-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- arch/um/os-Linux/signal.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 11f07f4982700..bebeb6b4bee8b 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -35,7 +35,6 @@ void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) = static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) { struct uml_pt_regs r; - int save_errno = errno; r.is_user = 0; if (sig == SIGSEGV) { @@ -49,8 +48,6 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) unblock_signals_trace(); (*sig_info[sig])(sig, si, &r, mc); - - errno = save_errno; } /* @@ -201,8 +198,11 @@ static void hard_handler(int sig, siginfo_t *si, void *p) { ucontext_t *uc = p; mcontext_t *mc = &uc->uc_mcontext; + int save_errno = errno; (*handlers[sig])(sig, (struct siginfo *)si, mc); + + errno = save_errno; } void set_handler(int sig) -- 2.51.0