Commit fd09d7fa authored Jul 03, 2009 by Sebastian Andrzej Siewior Committed by Herbert Xu Jul 03, 2009

crypto: ansi_prng - alloc cipher just in init



As reported by Eric Sesterhenn the re-allocation of the cipher in reset leads
to:
|BUG: sleeping function called from invalid context at kernel/rwsem.c:21
|in_atomic(): 1, irqs_disabled(): 0, pid: 4926, name: modprobe
|INFO: lockdep is turned off.
|Pid: 4926, comm: modprobe Tainted: G   M 2.6.31-rc1-22297-g5298976 #24
|Call Trace:
| [<c011dd93>] __might_sleep+0xf9/0x101
| [<c0777aa0>] down_read+0x16/0x68
| [<c048bf04>] crypto_alg_lookup+0x16/0x34
| [<c048bf52>] crypto_larval_lookup+0x30/0xf9
| [<c048c038>] crypto_alg_mod_lookup+0x1d/0x62
| [<c048c13e>] crypto_alloc_base+0x1e/0x64
| [<c04bf991>] reset_prng_context+0xab/0x13f
| [<c04e5cfc>] ? __spin_lock_init+0x27/0x51
| [<c04bfce1>] cprng_init+0x2a/0x42
| [<c048bb4c>] __crypto_alloc_tfm+0xfa/0x128
| [<c048c153>] crypto_alloc_base+0x33/0x64
| [<c04933c9>] alg_test_cprng+0x30/0x1f4
| [<c0493329>] alg_test+0x12f/0x19f
| [<c0177f1f>] ? __alloc_pages_nodemask+0x14d/0x481
| [<d09219e2>] do_test+0xf9d/0x163f [tcrypt]
| [<d0920de6>] do_test+0x3a1/0x163f [tcrypt]
| [<d0926035>] tcrypt_mod_init+0x35/0x7c [tcrypt]
| [<c010113c>] _stext+0x54/0x12c
| [<d0926000>] ? tcrypt_mod_init+0x0/0x7c [tcrypt]
| [<c01398a3>] ? up_read+0x16/0x2b
| [<c0139fc4>] ? __blocking_notifier_call_chain+0x40/0x4c
| [<c014ee8d>] sys_init_module+0xa9/0x1bf
| [<c010292b>] sysenter_do_call+0x12/0x32

because a spin lock is held and crypto_alloc_base() may sleep.
There is no reason to re-allocate the cipher, the state is resetted in
->setkey(). This patches makes the cipher allocation a one time thing and
moves it to init.

Reported-by: Eric Sesterhenn <eric.sesterhenn@lsexperts.de>
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

parent ed940700

crypto/ansi_cprng.c

+8 −17

Original line number	Diff line number	Diff line
		@@ -283,7 +283,6 @@ static int reset_prng_context(struct prng_context *ctx,
		unsigned char V, unsigned char DT)
		{
		int ret;
		int rc = -EINVAL;
		unsigned char *prng_key;

		spin_lock_bh(&ctx->prng_lock);
		@@ -307,34 +306,20 @@ static int reset_prng_context(struct prng_context *ctx,
		memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
		memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);

		if (ctx->tfm)
		crypto_free_cipher(ctx->tfm);

		ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
		if (IS_ERR(ctx->tfm)) {
		dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
		ctx);
		ctx->tfm = NULL;
		goto out;
		}

		ctx->rand_data_valid = DEFAULT_BLK_SZ;

		ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
		if (ret) {
		dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
		crypto_cipher_get_flags(ctx->tfm));
		crypto_free_cipher(ctx->tfm);
		goto out;
		}

		rc = 0;
		ret = 0;
		ctx->flags &= ~PRNG_NEED_RESET;
		out:
		spin_unlock_bh(&ctx->prng_lock);

		return rc;

		return ret;
		}

		static int cprng_init(struct crypto_tfm *tfm)
		@@ -342,6 +327,12 @@ static int cprng_init(struct crypto_tfm *tfm)
		struct prng_context *ctx = crypto_tfm_ctx(tfm);

		spin_lock_init(&ctx->prng_lock);
		ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
		if (IS_ERR(ctx->tfm)) {
		dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
		ctx);
		return PTR_ERR(ctx->tfm);
		}

		if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
		return -EINVAL;

Admin message