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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>
This commit is contained in:
Sebastian Andrzej Siewior 2009-07-03 12:10:47 +08:00 committed by Herbert Xu
parent ed94070058
commit fd09d7facb
1 changed files with 8 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
crypto/ansi_cprng.c
View File

@ -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;