| From | Ben Hutchings <> | Date | Mon, 21 Oct 2013 09:46:28 +0100 | Subject | [PATCH 3.2 060/149] crypto: api - Fix race condition in larval lookup |
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3.2.52-rc1 review patch. If anyone has any objections, please let me know.
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From: Herbert Xu <herbert@gondor.apana.org.au>
commit 77dbd7a95e4a4f15264c333a9e9ab97ee27dc2aa upstream.
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.
Reported-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- crypto/api.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/crypto/api.c +++ b/crypto/api.c @@ -34,6 +34,8 @@ EXPORT_SYMBOL_GPL(crypto_alg_sem); BLOCKING_NOTIFIER_HEAD(crypto_chain); EXPORT_SYMBOL_GPL(crypto_chain); +static struct crypto_alg *crypto_larval_wait(struct crypto_alg *alg); + static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg) { atomic_inc(&alg->cra_refcnt); @@ -150,8 +152,11 @@ static struct crypto_alg *crypto_larval_ } up_write(&crypto_alg_sem); - if (alg != &larval->alg) + if (alg != &larval->alg) { kfree(larval); + if (crypto_is_larval(alg)) + alg = crypto_larval_wait(alg); + } return alg; }
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