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 2B0F619CD18; Tue, 16 Jul 2024 14:25:28 +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=1721139929; cv=none; b=dDgc3BuEvmFEXyGE4ljdhRjwm+mjvYGcfzXvDNcGdJpUeT9ObqxhEotl8yZYFUp+wY1bIQ8im0lqHM5dDRezw+i16zQxSwcU5gLZS+YrnLGyeSS1XeA4M7g9DhMwz0qrdcyL6COOHMnxwqvNdPB9bZp9kTHkd1ICLGme6tuaxnQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721139929; c=relaxed/simple; bh=NLwybZFmejC88VgbyrRR2QeBOmfjeyD4rUgFrIOedjg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iZ8FbwUhxtkk3daWVu46k8EpIDG4jDVVTdTgbj7tv2Iaqgvi+ulmrVZDcpPSfOln7N+yWyYCoRDloKs3ijxdFt3JUmAjlDGUV5TSPnTNUVsOLTQBfdmkhoIRKwU37y/WTtPY2J+pNf0GQ64ZnfQMVH+z/ZzHJwOmHASpkUmDFLo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KRP8qUq7; 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="KRP8qUq7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06BCAC4AF0F; Tue, 16 Jul 2024 14:25:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721139928; bh=NLwybZFmejC88VgbyrRR2QeBOmfjeyD4rUgFrIOedjg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KRP8qUq7J0sAkIVl6MaFZBySPSjt/9csibA+bV1H7sAIKIY3VFSGpBnS4fbS9Wve/ SJ/DivlqaaMkvIjbgXGRyFoEU1myzegoozgqFRDpunJhAeEWcMqLXerRGu3TP+qJ/D Mj8NYlHnK1tepxl8URtrrVBXuLsd/m94TO0r6coz/OqqJxal9Li5pLcUW0tORe6/zV wKoadBKEVP7qIisI9+dLaAmlfyL71/smWaHM1q/3iCx/jerUY3wJnVHHnTw3KoFi5X XKUNCN8QxSYCBwPUxXVcCIbF62ZGsDFGciO+6sD1N1Y5B2L23JjUVmgOh7g/AH7Lyd mC2TLvofBlCtQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Anjali K , Vishal Chourasia , Srikar Dronamraju , Michael Ellerman , Sasha Levin , kees@kernel.org, npiggin@gmail.com, ruscur@russell.cc, aneesh.kumar@linux.ibm.com, christophe.leroy@csgroup.eu, linuxppc-dev@lists.ozlabs.org, linux-hardening@vger.kernel.org Subject: [PATCH AUTOSEL 6.9 03/22] powerpc/pseries: Whitelist dtl slub object for copying to userspace Date: Tue, 16 Jul 2024 10:24:10 -0400 Message-ID: <20240716142519.2712487-3-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240716142519.2712487-1-sashal@kernel.org> References: <20240716142519.2712487-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.9.9 Content-Transfer-Encoding: 8bit From: Anjali K [ Upstream commit 1a14150e1656f7a332a943154fc486504db4d586 ] Reading the dispatch trace log from /sys/kernel/debug/powerpc/dtl/cpu-* results in a BUG() when the config CONFIG_HARDENED_USERCOPY is enabled as shown below. kernel BUG at mm/usercopy.c:102! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries Modules linked in: xfs libcrc32c dm_service_time sd_mod t10_pi sg ibmvfc scsi_transport_fc ibmveth pseries_wdt dm_multipath dm_mirror dm_region_hash dm_log dm_mod fuse CPU: 27 PID: 1815 Comm: python3 Not tainted 6.10.0-rc3 #85 Hardware name: IBM,9040-MRX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1060.00 (NM1060_042) hv:phyp pSeries NIP: c0000000005d23d4 LR: c0000000005d23d0 CTR: 00000000006ee6f8 REGS: c000000120c078c0 TRAP: 0700 Not tainted (6.10.0-rc3) MSR: 8000000000029033 CR: 2828220f XER: 0000000e CFAR: c0000000001fdc80 IRQMASK: 0 [ ... GPRs omitted ... ] NIP [c0000000005d23d4] usercopy_abort+0x78/0xb0 LR [c0000000005d23d0] usercopy_abort+0x74/0xb0 Call Trace: usercopy_abort+0x74/0xb0 (unreliable) __check_heap_object+0xf8/0x120 check_heap_object+0x218/0x240 __check_object_size+0x84/0x1a4 dtl_file_read+0x17c/0x2c4 full_proxy_read+0x8c/0x110 vfs_read+0xdc/0x3a0 ksys_read+0x84/0x144 system_call_exception+0x124/0x330 system_call_vectored_common+0x15c/0x2ec --- interrupt: 3000 at 0x7fff81f3ab34 Commit 6d07d1cd300f ("usercopy: Restrict non-usercopy caches to size 0") requires that only whitelisted areas in slab/slub objects can be copied to userspace when usercopy hardening is enabled using CONFIG_HARDENED_USERCOPY. Dtl contains hypervisor dispatch events which are expected to be read by privileged users. Hence mark this safe for user access. Specify useroffset=0 and usersize=DISPATCH_LOG_BYTES to whitelist the entire object. Co-developed-by: Vishal Chourasia Signed-off-by: Vishal Chourasia Signed-off-by: Anjali K Reviewed-by: Srikar Dronamraju Signed-off-by: Michael Ellerman Link: https://msgid.link/20240614173844.746818-1-anjalik@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/platforms/pseries/setup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 284a6fa04b0c2..cba40d9d12848 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -343,8 +343,8 @@ static int alloc_dispatch_log_kmem_cache(void) { void (*ctor)(void *) = get_dtl_cache_ctor(); - dtl_cache = kmem_cache_create("dtl", DISPATCH_LOG_BYTES, - DISPATCH_LOG_BYTES, 0, ctor); + dtl_cache = kmem_cache_create_usercopy("dtl", DISPATCH_LOG_BYTES, + DISPATCH_LOG_BYTES, 0, 0, DISPATCH_LOG_BYTES, ctor); if (!dtl_cache) { pr_warn("Failed to create dispatch trace log buffer cache\n"); pr_warn("Stolen time statistics will be unreliable\n"); -- 2.43.0