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 AACA810965; Sat, 3 Feb 2024 04:14:00 +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=1706933640; cv=none; b=TLyICz7VDIwMSTkWN0h//4MzONwD1s2ukZOPZ70mrA8F4kXJnFQF8hNjwZEDl/chIT1njQ1Uc9xRBvN2Vm5mM/kjyDdOSZoS5li/NqjV2C0UhoIt0I5TgP+K2CDDAusqw+BJyzoimc3SZy7xFwbJWGZmB0cDc+DZFgU4K8SrnTA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706933640; c=relaxed/simple; bh=2fV1jUcdTju7MuHuXu6pnEdBYNjIbXD6pg9k9NwPMGQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=R447aWBjqVuhpRNbnzzX9rvPk0R79sQVyCvKdK7lWJAkxziYW6FFFn2EzUZupypmk3sZY31vXVP6xAJnu4QxdyWObntOxnoQRPPL9Der0m1wtSSg+v7DdcPtcLrtet0NTdZlvZiBZhjMtAoVYWRQRAtHI0Mf0nbMI2wIW7Yt4H8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=d/mrGqAm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="d/mrGqAm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16C27C433F1; Sat, 3 Feb 2024 04:14:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1706933640; bh=2fV1jUcdTju7MuHuXu6pnEdBYNjIbXD6pg9k9NwPMGQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d/mrGqAmxikQUmMJPP+OVJbD+IFLVq7a8+52vhKImqlTWU7a6HB/FpfMuM5wLKMhj /4NUOkAo5Jo4CAGi1SbIhQqW5ghm8eiZu+8Sv/a17upMG6qC2pfMvBLsPwemaRpEy9 qJ2JwJSTbsbD9/F8R19fX1HJITBXs/djik2O4hRw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Benjamin Berg , Richard Weinberger , Sasha Levin Subject: [PATCH 6.6 221/322] um: Dont use vfprintf() for os_info() Date: Fri, 2 Feb 2024 20:05:18 -0800 Message-ID: <20240203035406.375085232@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240203035359.041730947@linuxfoundation.org> References: <20240203035359.041730947@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Benjamin Berg [ Upstream commit 236f9fe39b02c15fa5530b53e9cca48354394389 ] The threads allocated inside the kernel have only a single page of stack. Unfortunately, the vfprintf function in standard glibc may use too much stack-space, overflowing it. To make os_info safe to be used by helper threads, use the kernel vscnprintf function into a smallish buffer and write out the information to stderr. Signed-off-by: Benjamin Berg Signed-off-by: Richard Weinberger Signed-off-by: Sasha Levin --- arch/um/os-Linux/util.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c index fc0f2a9dee5a..1dca4ffbd572 100644 --- a/arch/um/os-Linux/util.c +++ b/arch/um/os-Linux/util.c @@ -173,23 +173,38 @@ __uml_setup("quiet", quiet_cmd_param, "quiet\n" " Turns off information messages during boot.\n\n"); +/* + * The os_info/os_warn functions will be called by helper threads. These + * have a very limited stack size and using the libc formatting functions + * may overflow the stack. + * So pull in the kernel vscnprintf and use that instead with a fixed + * on-stack buffer. + */ +int vscnprintf(char *buf, size_t size, const char *fmt, va_list args); + void os_info(const char *fmt, ...) { + char buf[256]; va_list list; + int len; if (quiet_info) return; va_start(list, fmt); - vfprintf(stderr, fmt, list); + len = vscnprintf(buf, sizeof(buf), fmt, list); + fwrite(buf, len, 1, stderr); va_end(list); } void os_warn(const char *fmt, ...) { + char buf[256]; va_list list; + int len; va_start(list, fmt); - vfprintf(stderr, fmt, list); + len = vscnprintf(buf, sizeof(buf), fmt, list); + fwrite(buf, len, 1, stderr); va_end(list); } -- 2.43.0