linux_dsm_epyc7002/include
Eric Biggers af3ff8045b crypto: hmac - require that the underlying hash algorithm is unkeyed
Because the HMAC template didn't check that its underlying hash
algorithm is unkeyed, trying to use "hmac(hmac(sha3-512-generic))"
through AF_ALG or through KEYCTL_DH_COMPUTE resulted in the inner HMAC
being used without having been keyed, resulting in sha3_update() being
called without sha3_init(), causing a stack buffer overflow.

This is a very old bug, but it seems to have only started causing real
problems when SHA-3 support was added (requires CONFIG_CRYPTO_SHA3)
because the innermost hash's state is ->import()ed from a zeroed buffer,
and it just so happens that other hash algorithms are fine with that,
but SHA-3 is not.  However, there could be arch or hardware-dependent
hash algorithms also affected; I couldn't test everything.

Fix the bug by introducing a function crypto_shash_alg_has_setkey()
which tests whether a shash algorithm is keyed.  Then update the HMAC
template to require that its underlying hash algorithm is unkeyed.

Here is a reproducer:

    #include <linux/if_alg.h>
    #include <sys/socket.h>

    int main()
    {
        int algfd;
        struct sockaddr_alg addr = {
            .salg_type = "hash",
            .salg_name = "hmac(hmac(sha3-512-generic))",
        };
        char key[4096] = { 0 };

        algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
        bind(algfd, (const struct sockaddr *)&addr, sizeof(addr));
        setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key));
    }

Here was the KASAN report from syzbot:

    BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:341  [inline]
    BUG: KASAN: stack-out-of-bounds in sha3_update+0xdf/0x2e0  crypto/sha3_generic.c:161
    Write of size 4096 at addr ffff8801cca07c40 by task syzkaller076574/3044

    CPU: 1 PID: 3044 Comm: syzkaller076574 Not tainted 4.14.0-mm1+ #25
    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:341 [inline]
      sha3_update+0xdf/0x2e0 crypto/sha3_generic.c:161
      crypto_shash_update+0xcb/0x220 crypto/shash.c:109
      shash_finup_unaligned+0x2a/0x60 crypto/shash.c:151
      crypto_shash_finup+0xc4/0x120 crypto/shash.c:165
      hmac_finup+0x182/0x330 crypto/hmac.c:152
      crypto_shash_finup+0xc4/0x120 crypto/shash.c:165
      shash_digest_unaligned+0x9e/0xd0 crypto/shash.c:172
      crypto_shash_digest+0xc4/0x120 crypto/shash.c:186
      hmac_setkey+0x36a/0x690 crypto/hmac.c:66
      crypto_shash_setkey+0xad/0x190 crypto/shash.c:64
      shash_async_setkey+0x47/0x60 crypto/shash.c:207
      crypto_ahash_setkey+0xaf/0x180 crypto/ahash.c:200
      hash_setkey+0x40/0x90 crypto/algif_hash.c:446
      alg_setkey crypto/af_alg.c:221 [inline]
      alg_setsockopt+0x2a1/0x350 crypto/af_alg.c:254
      SYSC_setsockopt net/socket.c:1851 [inline]
      SyS_setsockopt+0x189/0x360 net/socket.c:1830
      entry_SYSCALL_64_fastpath+0x1f/0x96

Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-29 13:39:15 +11:00
..
acpi TTY/Serial patches for 4.15-rc1 2017-11-13 21:05:31 -08:00
asm-generic include/asm-generic/topology.h: remove unused parent_node() macro 2017-11-17 16:10:05 -08:00
clocksource arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
crypto crypto: hmac - require that the underlying hash algorithm is unkeyed 2017-11-29 13:39:15 +11:00
drm fixes/cleanups for rc1, non-desktop flags for VR 2017-11-23 21:04:56 -10:00
dt-bindings fixes/cleanups for rc1, non-desktop flags for VR 2017-11-23 21:04:56 -10:00
keys License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kvm KVM: arm/arm64: GICv4: Use the doorbell interrupt as an unblocking source 2017-11-10 09:43:22 +01:00
lib
linux Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:39:20 -08:00
math-emu
media media updates for v4.15-rc1 2017-11-15 20:30:12 -08:00
memory
misc
net net: accept UFO datagrams from tuntap and packet 2017-11-24 01:37:35 +09:00
pcmcia
ras License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rdma Updates for 4.15 kernel merge window 2017-11-15 14:54:53 -08:00
scsi scsi: Use 'blist_flags_t' for scsi_devinfo flags 2017-11-16 17:43:27 -05:00
soc We have two changes to the core framework this time around. The first being a 2017-11-17 20:04:24 -08:00
sound ALSA: hda - Fix yet remaining issue with vmaster 0dB initialization 2017-11-22 12:34:56 +01:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2017-11-24 19:19:20 -10:00
trace Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 13:43:25 -08:00
uapi Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2017-11-24 02:33:01 +09:00
video fbdev changes for v4.15: 2017-11-20 21:50:24 -10:00
xen xen: features and fixes for v4.15-rc1 2017-11-16 13:06:27 -08:00