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crypto: api - Fix race condition in larval lookup

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crypto_larval_lookup should only return a larval if it created one.
Any larval created by another entity must be processed through
crypto_larval_wait before being returned.

Otherwise this will lead to a larval being killed twice, which
will most likely lead to a crash.

Cc: stable@vger.kernel.org
Reported-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2013-09-08 14:33:50 +10:00
parent 6be48f2940
commit 77dbd7a95e
1 changed files with 6 additions and 1 deletions
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7
crypto/api.c
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@ -34,6 +34,8 @@ EXPORT_SYMBOL_GPL(crypto_alg_sem);
BLOCKING_NOTIFIER_HEAD(crypto_chain); BLOCKING_NOTIFIER_HEAD(crypto_chain);
EXPORT_SYMBOL_GPL(crypto_chain); EXPORT_SYMBOL_GPL(crypto_chain);
static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg);
struct crypto_alg *crypto_mod_get(struct crypto_alg *alg) struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
{ {
return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL; return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
@ -144,8 +146,11 @@ static struct crypto_alg *crypto_larval_add(const char *name, u32 type,
} }
up_write(&crypto_alg_sem); up_write(&crypto_alg_sem);
if (alg != &larval->alg) if (alg != &larval->alg) {
kfree(larval); kfree(larval);
if (crypto_is_larval(alg))
alg = crypto_larval_wait(alg);
}
return alg; return alg;
} }