diff options
| author | Herbert Xu <herbert@gondor.apana.org.au> | 2019-12-07 22:15:15 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-11 04:34:05 -0800 |
| commit | 8b0a3e013c1753b29cdfef99e3494b723cf59eb2 (patch) | |
| tree | 2962405b56af3b2c358c9fd76312f78cb34c244d /crypto/algapi.c | |
| parent | ede3b2392d527da83ef2bc76f0ff2b7795bfe21c (diff) | |
crypto: api - Fix race condition in crypto_spawn_alg
commit 73669cc556462f4e50376538d77ee312142e8a8a upstream.
The function crypto_spawn_alg is racy because it drops the lock
before shooting the dying algorithm. The algorithm could disappear
altogether before we shoot it.
This patch fixes it by moving the shooting into the locked section.
Fixes: 6bfd48096ff8 ("[CRYPTO] api: Added spawns")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'crypto/algapi.c')
| -rw-r--r-- | crypto/algapi.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/crypto/algapi.c b/crypto/algapi.c index 6d578b7e59a4..346557a3fc0b 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -659,22 +659,16 @@ EXPORT_SYMBOL_GPL(crypto_drop_spawn); static struct crypto_alg *crypto_spawn_alg(struct crypto_spawn *spawn) { struct crypto_alg *alg; - struct crypto_alg *alg2; down_read(&crypto_alg_sem); alg = spawn->alg; - alg2 = alg; - if (alg2) - alg2 = crypto_mod_get(alg2); - up_read(&crypto_alg_sem); - - if (!alg2) { - if (alg) - crypto_shoot_alg(alg); - return ERR_PTR(-EAGAIN); + if (alg && !crypto_mod_get(alg)) { + alg->cra_flags |= CRYPTO_ALG_DYING; + alg = NULL; } + up_read(&crypto_alg_sem); - return alg; + return alg ?: ERR_PTR(-EAGAIN); } struct crypto_tfm *crypto_spawn_tfm(struct crypto_spawn *spawn, u32 type, |