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| author | Herbert Xu <herbert@gondor.apana.org.au> | 2019-12-07 17:15:15 +0300 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2019-12-11 11:48:38 +0300 |
| commit | 73669cc556462f4e50376538d77ee312142e8a8a (patch) | |
| tree | db3ba895698e2e4886e668f4194ec008b2d0fd49 /crypto/algapi.c | |
| parent | 4a2abbc6b8683dd8ac399d305b23409a7a7503d3 (diff) | |
| download | linux-73669cc556462f4e50376538d77ee312142e8a8a.tar.xz | |
crypto: api - Fix race condition in crypto_spawn_alg
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>
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 9ecb4a57b342..54e844ad9364 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -679,22 +679,16 @@ 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, |