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 782794AEDA; Fri, 12 Apr 2024 07:34:52 +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=1712907292; cv=none; b=uHPMNUmyq1L9wafqFhxJJE3sT+9VpyqBkPJ3S+L+RPf3qIW6Lbmo4DsfNkef2qj6x94xP7Vy/4S3XAlhpOMoe0uNxoa3GH0Z2OMV49CpCl80VMGGakwTWZPVmNEmq+j5JZtAkcmQylgJYVQdjyfCUSYcX6x7UxEaRoukDTaO05k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712907292; c=relaxed/simple; bh=15F1o0wnaOSb0+2taQZ31Mu+Qemw7dCHw+75GzdsEBI=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=k7EtwuojKmquFdKWoJn5oxo+eVLwOfxSe2PM6v3uFMhGOHj5dyZ1J6Nn544RtZiCA0gtHmvHYWEsDGRDEjC5pjb8T1Y16iwCLCxbI4H+rJ6vVbTeHMkdfW4BzELBbzUI6EBeygjObQFPFPRA1EVr3a+kFDfEJEcsDb2YL7Ydyxs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=t3u9mTxX; 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="t3u9mTxX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 220E9C3277B; Fri, 12 Apr 2024 07:34:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712907292; bh=15F1o0wnaOSb0+2taQZ31Mu+Qemw7dCHw+75GzdsEBI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=t3u9mTxXzMRTHlaYd2D8ZzlmBV1GnOxQiRLlt1A4T+o67d0193/pfAl0YVCWJnKQK NTcbO3oeoHpxL7HGvLZA6LEkqBPettPejSlCKLgyY6aGupa4Tt64djRsdlqtDMWpZM WzsXxFAtAZcDpBiu90lgE9U5zM/imohuw2C+RMX4e2yQSVSinrp2Vbxc39gYVMIn3s mhyyfJZZjrN/KCGL2pdOssJhBtSOZZYHGcdDx7pOMA3+S23jMsz7RvBNuVOSVJyfDw otdkbBPqM6lmJVssuD9cYtYnbanjWtQVjS2+nw8dmx7aQcpisV6jdjKfBJZ+3YKDrm 9OSB0ZuyiKiEg== Date: Fri, 12 Apr 2024 16:34:48 +0900 From: Masami Hiramatsu (Google) To: qiang4.zhang@linux.intel.com Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Qiang Zhang , Stable@vger.kernel.org Subject: Re: [PATCH RESEND] bootconfig: use memblock_free_late to free xbc memory to buddy Message-Id: <20240412163448.98950acccc3baea1a3f07fed@kernel.org> In-Reply-To: <20240412024103.3078378-1-qiang4.zhang@linux.intel.com> References: <20240412024103.3078378-1-qiang4.zhang@linux.intel.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 12 Apr 2024 10:41:04 +0800 qiang4.zhang@linux.intel.com wrote: > From: Qiang Zhang > > On the time to free xbc memory, memblock has handed over memory to buddy > allocator. So it doesn't make sense to free memory back to memblock. > memblock_free() called by xbc_exit() even causes UAF bugs on architectures > with CONFIG_ARCH_KEEP_MEMBLOCK disabled like x86. Following KASAN logs > shows this case. > > [ 9.410890] ================================================================== > [ 9.418962] BUG: KASAN: use-after-free in memblock_isolate_range+0x12d/0x260 > [ 9.426850] Read of size 8 at addr ffff88845dd30000 by task swapper/0/1 > > [ 9.435901] CPU: 9 PID: 1 Comm: swapper/0 Tainted: G U 6.9.0-rc3-00208-g586b5dfb51b9 #5 > [ 9.446403] Hardware name: Intel Corporation RPLP LP5 (CPU:RaptorLake)/RPLP LP5 (ID:13), BIOS IRPPN02.01.01.00.00.19.015.D-00000000 Dec 28 2023 > [ 9.460789] Call Trace: > [ 9.463518] > [ 9.465859] dump_stack_lvl+0x53/0x70 > [ 9.469949] print_report+0xce/0x610 > [ 9.473944] ? __virt_addr_valid+0xf5/0x1b0 > [ 9.478619] ? memblock_isolate_range+0x12d/0x260 > [ 9.483877] kasan_report+0xc6/0x100 > [ 9.487870] ? memblock_isolate_range+0x12d/0x260 > [ 9.493125] memblock_isolate_range+0x12d/0x260 > [ 9.498187] memblock_phys_free+0xb4/0x160 > [ 9.502762] ? __pfx_memblock_phys_free+0x10/0x10 > [ 9.508021] ? mutex_unlock+0x7e/0xd0 > [ 9.512111] ? __pfx_mutex_unlock+0x10/0x10 > [ 9.516786] ? kernel_init_freeable+0x2d4/0x430 > [ 9.521850] ? __pfx_kernel_init+0x10/0x10 > [ 9.526426] xbc_exit+0x17/0x70 > [ 9.529935] kernel_init+0x38/0x1e0 > [ 9.533829] ? _raw_spin_unlock_irq+0xd/0x30 > [ 9.538601] ret_from_fork+0x2c/0x50 > [ 9.542596] ? __pfx_kernel_init+0x10/0x10 > [ 9.547170] ret_from_fork_asm+0x1a/0x30 > [ 9.551552] > > [ 9.555649] The buggy address belongs to the physical page: > [ 9.561875] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x45dd30 > [ 9.570821] flags: 0x200000000000000(node=0|zone=2) > [ 9.576271] page_type: 0xffffffff() > [ 9.580167] raw: 0200000000000000 ffffea0011774c48 ffffea0012ba1848 0000000000000000 > [ 9.588823] raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 > [ 9.597476] page dumped because: kasan: bad access detected > > [ 9.605362] Memory state around the buggy address: > [ 9.610714] ffff88845dd2ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > [ 9.618786] ffff88845dd2ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > [ 9.626857] >ffff88845dd30000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > [ 9.634930] ^ > [ 9.638534] ffff88845dd30080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > [ 9.646605] ffff88845dd30100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > [ 9.654675] ================================================================== > Oops, good catch! Indeed, it is too late to use memblock_free(). BTW, is it safe to call memblock_free_late() in early boot stage, because xbc_free_mem() will be called also from xbc_init(). If not, we need a custom internal __xbc_exit() or xbc_cleanup() which is called from xbc_init() and uses memblock_free(). Thank you, > Cc: Stable@vger.kernel.org > Signed-off-by: Qiang Zhang > --- > lib/bootconfig.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/bootconfig.c b/lib/bootconfig.c > index c59d26068a64..4524ee944df0 100644 > --- a/lib/bootconfig.c > +++ b/lib/bootconfig.c > @@ -63,7 +63,7 @@ static inline void * __init xbc_alloc_mem(size_t size) > > static inline void __init xbc_free_mem(void *addr, size_t size) > { > - memblock_free(addr, size); > + memblock_free_late(__pa(addr), size); > } > > #else /* !__KERNEL__ */ > -- > 2.39.2 > > -- Masami Hiramatsu (Google)