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 69CD51A2C24; Tue, 16 Jul 2024 14:30:28 +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=1721140228; cv=none; b=TITvMsCfO90mk4fqT1lnXFsHMyBGPCxWjfU7JvZH2Rso1WUGHrgCNsyUGCvEhB6c96TBpxiX07E6GFWNtMa+i2bzC7ZlSplAn9xAwxAcJ0S6/nbX5WVPg6aKoIlnBeDKWjz1IPH4ICIjxORDGTjnNM6gJYzc6N0lmKPmPW1Ij2Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721140228; c=relaxed/simple; bh=jyWYB67o19VLcwMYfZlKi8pc6TxN8bVl/Jq5LoXZXHk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wop8QyuTy0/EKuZaUEaCTwnqWE9e6/N1wYTZAnpG3R6oV2MQKHu3MyS1xWYwameb06IKLhvbAIWOcMpTnrM1Nxn7Juo6LLVD9hGafYelM1RPDSGZZ26LOVmOnFuTWUJfjDCEkXigbGg7WuSrttM341jXgINLB3cNYWhNJfYY7GE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Rh7SPLVV; 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="Rh7SPLVV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 645D5C116B1; Tue, 16 Jul 2024 14:30:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721140228; bh=jyWYB67o19VLcwMYfZlKi8pc6TxN8bVl/Jq5LoXZXHk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Rh7SPLVV2K2rd84LG5rz4s5gydhi3GHBQDnw72jVs18jfBGmf+luwhU/U1HRAVFPI XUXsy7lnVgej/aG9vppsWsnZ/bLHkiTWjOZUbCtZLNH4WtuLm7+i7XJM9U1mgpf796 O4PffnZXN+Z98A7ZaKpZCmPhdkkhtbVjaMe5Zd6cALBkClNZekqgGIVJb/F2xn8YtH 90m1DDwb1MJWwwpRqJZ22anJZz1JJWBqgCLsCrApj/vKaw6lBeOjUR4zKxbBDNZRQa wsnkSfgbgTP2rTojeK15Ob2Adw3LmYY0BZuvDE5T2cvr0pCSt1s7DePdTgMVjDmjEM XS8dK9cXdo0TQ== 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, arbab@linux.ibm.com, robh@kernel.org, christophe.leroy@csgroup.eu, aneesh.kumar@linux.ibm.com, ruscur@russell.cc, npiggin@gmail.com, linuxppc-dev@lists.ozlabs.org, linux-hardening@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 2/7] powerpc/pseries: Whitelist dtl slub object for copying to userspace Date: Tue, 16 Jul 2024 10:30:10 -0400 Message-ID: <20240716143021.2714348-2-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240716143021.2714348-1-sashal@kernel.org> References: <20240716143021.2714348-1-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 5.4.279 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 d5abb25865e36..bc1a4e024529b 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -305,8 +305,8 @@ 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