On Fri, Dec 22, 2017 at 11:22:38AM -0600, Eric Biggers wrote: > [+Cc keyrings@xxxxxxxxxxxxxxx] > > On Fri, Dec 22, 2017 at 07:55:01AM -0800, syzbot wrote: > > Hello, > > > > syzkaller hit the following crash on > > 9035a8961b504d0997369509ab8c6b1f0a4ee33d > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master > > compiler: gcc (GCC) 7.1.1 20170620 > > .config is attached > > Raw console output is attached. > > C reproducer is attached > > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > > for information about syzkaller reproducers > > > > > > audit: type=1400 audit(1513919078.260:7): avc: denied { map } for > > pid=3152 comm="syzkaller717822" path="/root/syzkaller717822551" dev="sda1" > > ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 > > tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 > > ================================================================== > > BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:344 [inline] > > BUG: KASAN: slab-out-of-bounds in sha3_update+0xdf/0x2e0 > > crypto/sha3_generic.c:161 > > Write of size 192 at addr ffff8801cf0e3b3c by task syzkaller717822/3152 > > > > CPU: 0 PID: 3152 Comm: syzkaller717822 Not tainted 4.15.0-rc4+ #232 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:17 [inline] > > dump_stack+0x194/0x257 lib/dump_stack.c:53 > > print_address_description+0x73/0x250 mm/kasan/report.c:252 > > kasan_report_error mm/kasan/report.c:351 [inline] > > kasan_report+0x25b/0x340 mm/kasan/report.c:409 > > check_memory_region_inline mm/kasan/kasan.c:260 [inline] > > check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 > > memcpy+0x37/0x50 mm/kasan/kasan.c:303 > > memcpy include/linux/string.h:344 [inline] > > sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161 > > crypto_shash_update+0xda/0x240 crypto/shash.c:110 > > hmac_update+0x7e/0xa0 crypto/hmac.c:122 > > crypto_shash_update+0xda/0x240 crypto/shash.c:110 > > kdf_ctr security/keys/dh.c:181 [inline] > > keyctl_dh_compute_kdf security/keys/dh.c:226 [inline] > > __keyctl_dh_compute+0x160f/0x1990 security/keys/dh.c:398 > > keyctl_dh_compute+0xac/0xf3 security/keys/dh.c:434 > > SYSC_keyctl security/keys/keyctl.c:1741 [inline] > > SyS_keyctl+0x72/0x2c0 security/keys/keyctl.c:1637 > > entry_SYSCALL_64_fastpath+0x1f/0x96 > > RIP: 0033:0x43feb9 > > RSP: 002b:00007ffd3aef51a8 EFLAGS: 00000217 ORIG_RAX: 00000000000000fa > > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043feb9 > > RDX: 0000000020c2cfff RSI: 00000000204c8ff4 RDI: 0000000000000017 > > RBP: 00000000006ca018 R08: 00000000208e6fd4 R09: 0000000000000000 > > R10: 0000000000000001 R11: 0000000000000217 R12: 0000000000401820 > > R13: 00000000004018b0 R14: 0000000000000000 R15: 0000000000000000 > > > > Allocated by task 3152: > > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > > set_track mm/kasan/kasan.c:459 [inline] > > kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 > > __do_kmalloc mm/slab.c:3708 [inline] > > __kmalloc+0x162/0x760 mm/slab.c:3717 > > kmalloc include/linux/slab.h:504 [inline] > > kdf_alloc security/keys/dh.c:111 [inline] > > __keyctl_dh_compute+0x2b0/0x1990 security/keys/dh.c:288 > > keyctl_dh_compute+0xac/0xf3 security/keys/dh.c:434 > > SYSC_keyctl security/keys/keyctl.c:1741 [inline] > > SyS_keyctl+0x72/0x2c0 security/keys/keyctl.c:1637 > > entry_SYSCALL_64_fastpath+0x1f/0x96 > > > > Freed by task 1637: > > save_stack+0x43/0xd0 mm/kasan/kasan.c:447 > > set_track mm/kasan/kasan.c:459 [inline] > > kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 > > __cache_free mm/slab.c:3488 [inline] > > kfree+0xd6/0x260 mm/slab.c:3803 > > kernfs_fop_release+0x13f/0x180 fs/kernfs/file.c:783 > > __fput+0x327/0x7e0 fs/file_table.c:210 > > ____fput+0x15/0x20 fs/file_table.c:244 > > task_work_run+0x199/0x270 kernel/task_work.c:113 > > tracehook_notify_resume include/linux/tracehook.h:191 [inline] > > exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 > > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > > syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 > > entry_SYSCALL_64_fastpath+0x94/0x96 > > > > The problem is that KEYCTL_DH_COMPUTE allows the user to request and use any > hash algorithm as an unkeyed hash without checking whether it is in fact > unkeyed. > > We could fix this by checking for !crypto_shash_alg_has_setkey() after > allocating the hash, but now I'd really like to solve this for all users by > having crypto_[as]hash_init() and crypto_[as]hash_digest() automatically return > -ENOKEY if a key is needed and one hasn't been set. That would also have solved > the bug I fixed specifically for HMAC by "crypto: hmac - require that the > underlying hash algorithm is unkeyed". > > Eric Fixed in cryptodev/master by: #syz fix: crypto: hash - prevent using keyed hashes without setting key
