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| 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 04:35:31 -0800 |
| commit | f0a235bd332c3568b2b1b7d32c08a5dfc02c3b64 (patch) | |
| tree | 67754e75e47f6c9adb056987beff434dcb293dea /crypto/algapi.c | |
| parent | a9edfdb29f48bdea757bbd057cab816edf58b4d2 (diff) | |
| download | linux-crypto-f0a235bd332c3568b2b1b7d32c08a5dfc02c3b64.tar.gz linux-crypto-f0a235bd332c3568b2b1b7d32c08a5dfc02c3b64.zip | |
crypto: api - Fix race condition in crypto_spawn_alg
commit bc1d8cb6169a2deb7dbcad8ac6ed8ade1bc2bb05 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: 525ed3dcb430 ("[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 5167a4f6..bb8329e4 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -697,22 +697,16 @@ 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, |