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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553108242; bh=jU9CC7/cwUq1tn+oMCzXLh4scS18THRBZAue4BKsS7g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aWPdUEOCxrvBlwDE+7K2wdjzuuigEDqZTaAD+vsE1JIMwEnZkBxK0E6Tk8a7ZEGj6 IUXiiFPhx9crVD9zlnZpaBDlDWvI4qPTJlGJtoYALy7RJlA2xgYpcDNV5NOkWAwmlm P1lYonc179XpoR+OPMvwkl92YibgKft0h7rTS7Ss= Date: Wed, 20 Mar 2019 11:57:20 -0700 From: Eric Biggers To: Kees Cook Subject: Re: crypto: Kernel memory overwrite attempt detected to spans multiple pages Message-ID: <20190320185719.GB180195@gmail.com> References: <20190319170911.GB202956@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190319170911.GB202956@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190320_115722_933458_5B76C3A4 X-CRM114-Status: GOOD ( 17.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Herbert Xu , Linux Kernel Mailing List , linux-security-module@vger.kernel.org, Geert Uytterhoeven , Linux Crypto Mailing List , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Mar 19, 2019 at 10:09:13AM -0700, Eric Biggers wrote: > On Tue, Mar 19, 2019 at 12:54:23PM +0100, Geert Uytterhoeven wrote: > > When running the sha1-asm crypto selftest on arm with > > CONFIG_HARDENED_USERCOPY_PAGESPAN=y: > > > > usercopy: Kernel memory overwrite attempt detected to spans > > multiple pages (offset 0, size 42)! > > ------------[ cut here ]------------ > > kernel BUG at mm/usercopy.c:102! > > Internal error: Oops - BUG: 0 [#1] SMP ARM > > Modules linked in: > > CPU: 0 PID: 35 Comm: cryptomgr_test Not tainted > > 5.1.0-rc1-koelsch-01109-gbeb7d6376ecfbf07-dirty #397 > > Hardware name: Generic R-Car Gen2 (Flattened Device Tree) > > PC is at usercopy_abort+0x68/0x90 > > LR is at usercopy_abort+0x68/0x90 > > pc : [] lr : [] psr: 60000013 > > sp : ea54bc60 ip : 00000010 fp : cccccccd > > r10: 00000000 r9 : c0e0ce04 r8 : ea54d009 > > r7 : ea54d00a r6 : 00000000 r5 : 0000002a r4 : c09d1120 > > r3 : dd6cd422 r2 : dd6cd422 r1 : 2abb4000 r0 : 0000005f > > Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user > > Control: 30c5387d Table: 40003000 DAC: fffffffd > > Process cryptomgr_test (pid: 35, stack limit = 0x(ptrval)) > > Stack: (0xea54bc60 to 0xea54c000) > > bc60: c09d1120 c09d1120 c09d1120 00000000 0000002a 0000002a > > 00000000 c0310060 > > bc80: 0000002a 00000000 000001c0 00000000 00000000 c0eb11e8 > > ea54cfe0 ea538c00 > > bca0: 00000000 ea54cfe0 ebef73e0 0000002a ea538c20 ea54bd84 > > 0000003a c0427a30 > > bcc0: ea54bdbc 00000000 00000000 c081cf70 eb074280 c081cf70 > > 0000002a c081cf80 > > bce0: 0000000e c07da138 ea54bd0c 00000000 c084061c c04248e8 > > c0e0a408 eb074240 > > bd00: eb074200 c04253c8 eb074280 ea550000 00000012 dd6cd422 > > ebef7480 eb074200 > > bd20: ea54bd84 c081cf64 ea537200 00000002 00000000 00000014 > > c084061c c0428c38 > > bd40: ea54bd84 ea54bdbc c081cd34 00000000 c0e4e4b4 ea538c40 > > 00000002 eabe4e80 > > bd60: ea538c00 00000400 ea4f7a00 ea4f7a60 eb074240 00000060 > > 00000006 c09d544c > > bd80: 00000038 00000003 00000000 00000038 ea54bd7c 00000001 > > eb074200 00000000 > > bda0: 00000000 dead4ead ffffffff ffffffff ea54bdb0 ea54bdb0 > > 00000000 c081cf70 > > bdc0: c081ce68 c081ce78 ea4f7480 eb000780 00000dc0 eb000780 > > c0e4ee80 443e9884 > > bde0: 6ed23b1c a14aaeba e52951f9 f17046e5 fefefefe fefefefe > > fefefefe fefefefe > > be00: eb000780 c04292c4 c0e0a638 60000013 60000013 c0305298 > > ea4f7a00 c03062bc > > be20: eb000780 00000cc0 ea4f7a00 dd6cd422 00000cc0 ea538c00 > > 00000002 eabe4e40 > > be40: ea537200 00000007 00000000 ea4f7a00 eb074200 c0429314 > > eb074200 ea538c00 > > be60: ea4f7a00 0000000a eabe4e80 c084061c c08405fc 00000006 > > c04dace8 00000006 > > be80: 00000000 c084065c ea537200 0000000e 00000400 eb04de08 > > ea4f71a8 c0429420 > > bea0: 00000400 ea537200 0000000e ea537200 0000000e c0429374 > > 00000400 ffffffff > > bec0: 000000a2 c042a414 00000103 c0e0a408 00000000 c0e0a438 > > c0e5a2a0 c0e5a2a0 > > bee0: 00000001 00000001 00000017 ffffe000 00000000 60000013 > > c0e5a2a0 c0269470 > > bf00: c09c9ed0 ea54bf5c 00000103 00000000 00000000 c0e0a408 > > ea537280 0000000e > > bf20: 00000400 c0426500 00000000 eb04de08 ea4f71a8 c02694f4 > > c09c9ed0 ea54bf5c > > bf40: ea54bf28 c02699d0 ea54bf5c dd6cd422 ea537200 dd6cd422 > > c09c9ed0 ea537200 > > bf60: ea4af1c0 ea54a000 ea537200 c0426500 00000000 eb04de08 > > ea4f71a8 c0426524 > > bf80: ea4f7180 c023dcec ea54a000 ea4af1c0 c023dbb4 00000000 > > 00000000 00000000 > > bfa0: 00000000 00000000 00000000 c02010d8 00000000 00000000 > > 00000000 00000000 > > bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 > > 00000000 00000000 > > bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 > > 00000000 00000000 > > [] (usercopy_abort) from [] > > (__check_object_size+0x2d8/0x448) > > [] (__check_object_size) from [] > > (build_test_sglist+0x268/0x2d8) > > [] (build_test_sglist) from [] > > (test_hash_vec_cfg+0x110/0x694) > > [] (test_hash_vec_cfg) from [] > > (__alg_test_hash+0x158/0x1b8) > > [] (__alg_test_hash) from [] (alg_test_hash+0xac/0xf4) > > [] (alg_test_hash) from [] (alg_test.part.4+0x264/0x2f8) > > [] (alg_test.part.4) from [] (cryptomgr_test+0x24/0x44) > > [] (cryptomgr_test) from [] (kthread+0x138/0x150) > > [] (kthread) from [] (ret_from_fork+0x14/0x3c) > > Exception stack(0xea54bfb0 to 0xea54bff8) > > bfa0: 00000000 00000000 > > 00000000 00000000 > > bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 > > 00000000 00000000 > > bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 > > Code: e58de000 e98d0012 e1a0100c ebfd6712 (e7f001f2) > > ---[ end trace 190b3cf48e720f78 ]--- > > BUG: sleeping function called from invalid context at > > include/linux/percpu-rwsem.h:34 > > in_atomic(): 0, irqs_disabled(): 128, pid: 35, name: cryptomgr_test > > CPU: 0 PID: 35 Comm: cryptomgr_test Tainted: G D > > 5.1.0-rc1-koelsch-01109-gbeb7d6376ecfbf07-dirty #397 > > Hardware name: Generic R-Car Gen2 (Flattened Device Tree) > > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > > [] (show_stack) from [] (dump_stack+0x7c/0x9c) > > [] (dump_stack) from [] (___might_sleep+0xf4/0x158) > > [] (___might_sleep) from [] (exit_signals+0x2c/0x258) > > [] (exit_signals) from [] (do_exit+0x114/0xa20) > > [] (do_exit) from [] (die+0x304/0x344) > > [] (die) from [] (do_undefinstr+0x80/0x190) > > [] (do_undefinstr) from [] (__und_svc_finish+0x0/0x3c) > > Exception stack(0xea54bc10 to 0xea54bc58) > > bc00: 0000005f 2abb4000 > > dd6cd422 dd6cd422 > > bc20: c09d1120 0000002a 00000000 ea54d00a ea54d009 c0e0ce04 > > 00000000 cccccccd > > bc40: 00000010 ea54bc60 c030fd60 c030fd60 60000013 ffffffff > > [] (__und_svc_finish) from [] (usercopy_abort+0x68/0x90) > > [] (usercopy_abort) from [] > > (__check_object_size+0x2d8/0x448) > > [] (__check_object_size) from [] > > (build_test_sglist+0x268/0x2d8) > > [] (build_test_sglist) from [] > > (test_hash_vec_cfg+0x110/0x694) > > [] (test_hash_vec_cfg) from [] > > (__alg_test_hash+0x158/0x1b8) > > [] (__alg_test_hash) from [] (alg_test_hash+0xac/0xf4) > > [] (alg_test_hash) from [] (alg_test.part.4+0x264/0x2f8) > > [] (alg_test.part.4) from [] (cryptomgr_test+0x24/0x44) > > [] (cryptomgr_test) from [] (kthread+0x138/0x150) > > [] (kthread) from [] (ret_from_fork+0x14/0x3c) > > Exception stack(0xea54bfb0 to 0xea54bff8) > > bfa0: 00000000 00000000 > > 00000000 00000000 > > bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 > > 00000000 00000000 > > bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 > > > > Well, this must happen with the new (in 5.1) crypto self-tests implementation > for any crypto algorithm when CONFIG_HARDENED_USERCOPY_PAGESPAN=y. I don't > understand why hardened usercopy considers it a bug though, as there's no buffer > overflow. The crypto tests use copy_from_iter() to copy data into a 2-page > buffer that was allocated with __get_free_pages(): > > __get_free_pages(GFP_KERNEL, 1) > > ... where 1 means an order-1 allocation. > > If it copies to offset=4064 len=42, for example, then hardened usercopy > considers it a bug even though the buffer is 8192 bytes long. Why? > > It isn't actually copying anything to/from userspace, BTW; it's using iov_iter > with ITER_KVEC. > > - Eric Kees, any thoughts on why hardened usercopy rejects copies spanning a page boundary when they seem to be fine? - Eric _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel