On 12/14/2016 11:39 AM, Herbert Xu wrote: > On Tue, Dec 13, 2016 at 01:34:02PM +0000, Ard Biesheuvel wrote: >> The new skcipher walk API may crash in the following way. (Interestingly, >> the tcrypt boot time tests seem unaffected, while an explicit test using >> the module triggers it) >> >> Unable to handle kernel NULL pointer dereference at virtual address 00000000 >> ... >> [<ffff000008431d84>] __memcpy+0x84/0x180 >> [<ffff0000083ec0d0>] skcipher_walk_done+0x328/0x340 >> [<ffff0000080c5c04>] ctr_encrypt+0x84/0x100 >> [<ffff000008406d60>] simd_skcipher_encrypt+0x88/0x98 >> [<ffff0000083fa05c>] crypto_rfc3686_crypt+0x8c/0x98 >> [<ffff0000009b0900>] test_skcipher_speed+0x518/0x820 [tcrypt] >> [<ffff0000009b31c0>] do_test+0x1408/0x3b70 [tcrypt] >> [<ffff0000009bd050>] tcrypt_mod_init+0x50/0x1000 [tcrypt] >> [<ffff0000080838f4>] do_one_initcall+0x44/0x138 >> [<ffff0000081aee60>] do_init_module+0x68/0x1e0 >> [<ffff0000081524d0>] load_module+0x1fd0/0x2458 >> [<ffff000008152c38>] SyS_finit_module+0xe0/0xf0 >> [<ffff0000080836f0>] el0_svc_naked+0x24/0x28 >> >> This is due to the fact that skcipher_done_slow() may be entered with >> walk->buffer unset. Since skcipher_walk_done() already deals with the >> case where walk->buffer == walk->page, it appears to be the intention >> that walk->buffer point to walk->page after skcipher_next_slow(), so >> ensure that is the case. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > > Patch applied. Thanks. Fixed problem here as well... Tested-by: Milan Broz <gmazyland@xxxxxxxxx> Without patch, just running cryptsetup tests (make check) on 32bit machine I get kernel crash in LRW mode. For me, the problem can be triggered from the userspace crypto API (no root needed!) dd if=/dev/zero of=test bs=1M count=32 echo blah | /sbin/cryptsetup luksFormat test -c aes-lrw-null -q --use-urandom and I get Dec 15 13:00:50 kernel: NET: Registered protocol family 38 Dec 15 13:00:50 kernel: BUG: unable to handle kernel NULL pointer dereference at (null) Dec 15 13:00:50 kernel: IP: memcpy+0xf/0x20 Dec 15 13:00:50 kernel: *pde = 00000000 Dec 15 13:00:50 kernel: Dec 15 13:00:50 kernel: Oops: 0000 [#1] PREEMPT SMP Dec 15 13:00:50 kernel: Modules linked in: lrw algif_skcipher af_alg loop rpcsec_gss_krb5 dm_mod crc32_pclmul crc32c_intel pcbc aesni_intel aes_i586 crypto_simd cryptd ata_piix Dec 15 13:00:50 kernel: CPU: 0 PID: 1667 Comm: cryptsetup Tainted: G W 4.9.0+ #122 Dec 15 13:00:50 kernel: Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015 Dec 15 13:00:50 kernel: task: f5cc66c0 task.stack: f45e6000 Dec 15 13:00:50 kernel: EIP: memcpy+0xf/0x20 Dec 15 13:00:50 kernel: EFLAGS: 00010202 CPU: 0 Dec 15 13:00:50 kernel: EAX: fffbaffc EBX: 00000004 ECX: 00000001 EDX: 00000000 Dec 15 13:00:50 kernel: ESI: 00000000 EDI: fffbaffc EBP: f45e7d48 ESP: f45e7d3c Dec 15 13:00:50 kernel: DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 Dec 15 13:00:50 kernel: CR0: 80050033 CR2: 00000000 CR3: 35eba000 CR4: 001406d0 Dec 15 13:00:50 kernel: Call Trace: Dec 15 13:00:50 kernel: scatterwalk_copychunks+0x75/0xd0 Dec 15 13:00:50 kernel: skcipher_walk_done+0x2b1/0x300 Dec 15 13:00:50 kernel: pre_crypt+0x230/0x350 [lrw] Dec 15 13:00:50 kernel: ? __kmalloc+0x222/0x270 Dec 15 13:00:50 kernel: do_decrypt+0x27/0xb0 [lrw] Dec 15 13:00:50 kernel: decrypt+0x19/0x20 [lrw] Dec 15 13:00:50 kernel: skcipher_recvmsg+0x2d3/0x6c0 [algif_skcipher] Dec 15 13:00:50 kernel: ? trace_hardirqs_on_caller+0xd6/0x200 Dec 15 13:00:50 kernel: ? release_sock+0x63/0x90 Dec 15 13:00:50 kernel: ? trace_hardirqs_on+0xb/0x10 Dec 15 13:00:50 kernel: ? __local_bh_enable_ip+0x5c/0xd0 Dec 15 13:00:50 kernel: ? _raw_spin_unlock_bh+0x2a/0x30 Dec 15 13:00:50 kernel: skcipher_recvmsg_nokey+0x26/0x38 [algif_skcipher] Dec 15 13:00:50 kernel: sock_read_iter+0x77/0xb0 Dec 15 13:00:50 kernel: __vfs_read+0xaa/0x120 Dec 15 13:00:50 kernel: vfs_read+0x72/0x100 Dec 15 13:00:50 kernel: SyS_read+0x3d/0xa0 Dec 15 13:00:50 kernel: do_int80_syscall_32+0x40/0x110 Dec 15 13:00:50 kernel: entry_INT80_32+0x2f/0x2f Dec 15 13:00:50 kernel: EIP: 0xb77cc9f2 Dec 15 13:00:50 kernel: EFLAGS: 00000246 CPU: 0 Dec 15 13:00:50 kernel: EAX: ffffffda EBX: 00000006 ECX: bff01f4c EDX: 00000200 Dec 15 13:00:50 kernel: ESI: 00000030 EDI: fffffffb EBP: bff01e78 ESP: bff01dd4 Dec 15 13:00:50 kernel: DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b Dec 15 13:00:50 kernel: Code: fc ff ff 8b 43 58 2b 43 50 88 43 4e 5b 5d c3 90 90 90 90 90 90 90 90 90 90 90 90 90 55 89 e5 57 89 c7 56 89 d6 53 89 cb c1 e9 02 <f3> a5 89 d9 83 e1 03 74 02 f3 a4 5b 5e 5f 5d c3 90 55 89 e5 57 Dec 15 13:00:50 kernel: EIP: memcpy+0xf/0x20 SS:ESP: 0068:f45e7d3c Dec 15 13:00:50 kernel: CR2: 0000000000000000 Dec 15 13:00:50 kernel: ---[ end trace 6d5fbbd95de42602 ]--- Dec 15 13:00:50 kernel: note: cryptsetup[1667] exited with preempt_count 1 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
