[PATCH] crypto: ahash - Set using_shash for cloned ahash wrapper over shash

[Dmitry Safonov]

The cloned child of ahash that uses shash under the hood should use
shash helpers (like crypto_shash_setkey()).

The following panic may be observed on TCP-AO selftests:

> ==================================================================
> BUG: KASAN: wild-memory-access in crypto_mod_get+0x1b/0x60
> Write of size 4 at addr 5d5be0ff5c415e14 by task connect_ipv4/1397
>
> CPU: 0 PID: 1397 Comm: connect_ipv4 Tainted: G        W          6.6.0+ #47
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x46/0x70
>  kasan_report+0xc3/0xf0
>  kasan_check_range+0xec/0x190
>  crypto_mod_get+0x1b/0x60
>  crypto_spawn_alg+0x53/0x140
>  crypto_spawn_tfm2+0x13/0x60
>  hmac_init_tfm+0x25/0x60
>  crypto_ahash_setkey+0x8b/0x100
>  tcp_ao_add_cmd+0xe7a/0x1120
>  do_tcp_setsockopt+0x5ed/0x12a0
>  do_sock_setsockopt+0x82/0x100
>  __sys_setsockopt+0xe9/0x160
>  __x64_sys_setsockopt+0x60/0x70
>  do_syscall_64+0x3c/0xe0
>  entry_SYSCALL_64_after_hwframe+0x46/0x4e
> ==================================================================
> general protection fault, probably for non-canonical address 0x5d5be0ff5c415e14: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 1397 Comm: connect_ipv4 Tainted: G    B   W          6.6.0+ #47
> Call Trace:
>  <TASK>
>  ? die_addr+0x3c/0xa0
>  ? exc_general_protection+0x144/0x210
>  ? asm_exc_general_protection+0x22/0x30
>  ? add_taint+0x26/0x90
>  ? crypto_mod_get+0x20/0x60
>  ? crypto_mod_get+0x1b/0x60
>  ? ahash_def_finup_done1+0x58/0x80
>  crypto_spawn_alg+0x53/0x140
>  crypto_spawn_tfm2+0x13/0x60
>  hmac_init_tfm+0x25/0x60
>  crypto_ahash_setkey+0x8b/0x100
>  tcp_ao_add_cmd+0xe7a/0x1120
>  do_tcp_setsockopt+0x5ed/0x12a0
>  do_sock_setsockopt+0x82/0x100
>  __sys_setsockopt+0xe9/0x160
>  __x64_sys_setsockopt+0x60/0x70
>  do_syscall_64+0x3c/0xe0
>  entry_SYSCALL_64_after_hwframe+0x46/0x4e
>  </TASK>
> RIP: 0010:crypto_mod_get+0x20/0x60

Make sure that the child/clone has using_shash set when parent is
an shash user.

Fixes: 2f1f34c1bf7b ("crypto: ahash - optimize performance when wrapping shash")
Cc: David Ahern <dsahern@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Francesco Ruggeri <fruggeri05@xxxxxxxxx>
To: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Cc: Salam Noureddine <noureddine@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
---
 crypto/ahash.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/crypto/ahash.c b/crypto/ahash.c
index deee55f939dc..80c3e5354711 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -651,6 +651,7 @@ struct crypto_ahash *crypto_clone_ahash(struct crypto_ahash *hash)
 			err = PTR_ERR(shash);
 			goto out_free_nhash;
 		}
+		nhash->using_shash = true;
 		*nctx = shash;
 		return nhash;
 	}

base-commit: be3ca57cfb777ad820c6659d52e60bbdd36bf5ff
-- 
2.42.0