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 7E8401E6321; Tue, 15 Oct 2024 13:08:25 +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=1728997705; cv=none; b=pD6phZg7EngIBz7WI8Eh7wlObqHCzYYHOHVkMwbr8PuVsXBidWbc9bYJJ0AZwxyWo75UpZo0hcORkIOv2Xpc13u4kEc5A6OiRd4Z/a1lBIHhFrOxFotFqi0I7cGCDB8MG2V3VeLrSNvBDUhKpxgC1gEvkZkfimDYtgjagxh/OX0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728997705; c=relaxed/simple; bh=jcbpVEyth8SPWGERu3oZcOluGafSgQb0wO6PPERLGeg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aThleIrdw7ygj/CEOp6JeKoRRwzPEVDYSie/V13PI9haVqvqec37yNmJxjRS0OO1iVP2dIPA/Pd93k4MZ/jxePp78aC+QulHD73YzGkaS5Q7/b4raS7n1+E7D8I9N8QSWR09b6G37LMILwLPGW2wFpJc9TZ4Vo8HbByCQ9xnePQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CrBdnTud; 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="CrBdnTud" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0056AC4CEC6; Tue, 15 Oct 2024 13:08:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728997705; bh=jcbpVEyth8SPWGERu3oZcOluGafSgQb0wO6PPERLGeg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CrBdnTud8+NAyGokHZ9S0lMzdiVAd73eDwZyvx0FHdbGSwWLsMzzS+UuvhDgBtXE/ ukC5I1Nv+tfzI2qz6BazDTGyBqh9kOt+6HajDoU2I51OFaKhIUdVWZ7M5kwZP40IQv QlLeJt69wWHiOoaQNvawF/349NUgpJ7HVCHNVWQY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Gow , Kees Cook , Alexandre Ghiti , Linus Walleij , Luis Chamberlain , Mark Rutland , Russell King , Andrew Morton Subject: [PATCH 5.10 261/518] mm: only enforce minimum stack gap size if its sensible Date: Tue, 15 Oct 2024 14:42:45 +0200 Message-ID: <20241015123927.067058112@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015123916.821186887@linuxfoundation.org> References: <20241015123916.821186887@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Gow commit 69b50d4351ed924f29e3d46b159e28f70dfc707f upstream. The generic mmap_base code tries to leave a gap between the top of the stack and the mmap base address, but enforces a minimum gap size (MIN_GAP) of 128MB, which is too large on some setups. In particular, on arm tasks without ADDR_LIMIT_32BIT, the STACK_TOP value is less than 128MB, so it's impossible to fit such a gap in. Only enforce this minimum if MIN_GAP < MAX_GAP, as we'd prefer to honour MAX_GAP, which is defined proportionally, so scales better and always leaves us with both _some_ stack space and some room for mmap. This fixes the usercopy KUnit test suite on 32-bit arm, as it doesn't set any personality flags so gets the default (in this case 26-bit) task size. This test can be run with: ./tools/testing/kunit/kunit.py run --arch arm usercopy --make_options LLVM=1 Link: https://lkml.kernel.org/r/20240803074642.1849623-2-davidgow@google.com Fixes: dba79c3df4a2 ("arm: use generic mmap top-down layout and brk randomization") Signed-off-by: David Gow Reviewed-by: Kees Cook Cc: Alexandre Ghiti Cc: Linus Walleij Cc: Luis Chamberlain Cc: Mark Rutland Cc: Russell King Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/util.c +++ b/mm/util.c @@ -418,7 +418,7 @@ static unsigned long mmap_base(unsigned if (gap + pad > gap) gap += pad; - if (gap < MIN_GAP) + if (gap < MIN_GAP && MIN_GAP < MAX_GAP) gap = MIN_GAP; else if (gap > MAX_GAP) gap = MAX_GAP;