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authorHerbert Xu <herbert@gondor.apana.org.au>2020-04-10 16:09:42 +1000
committerHerbert Xu <herbert@gondor.apana.org.au>2020-04-16 16:49:22 +1000
commit6603523bf5e432c7c8490fb500793bb15d4e5f61 (patch)
treea55f489fb787cdc482819bcf29a1a0327549637e /crypto/api.c
parenteebac678556d6927f09a992872f4464cf3aecc76 (diff)
crypto: api - Fix use-after-free and race in crypto_spawn_alg
There are two problems in crypto_spawn_alg. First of all it may return spawn->alg even if spawn->dead is set. This results in a double-free as detected by syzbot. Secondly the setting of the DYING flag is racy because we hold the read-lock instead of the write-lock. We should instead call crypto_shoot_alg in a safe manner by gaining a refcount, dropping the lock, and then releasing the refcount. This patch fixes both problems. Reported-by: syzbot+fc0674cde00b66844470@syzkaller.appspotmail.com Fixes: 4f87ee118d16 ("crypto: api - Do not zap spawn->alg") Fixes: 73669cc55646 ("crypto: api - Fix race condition in...") Cc: <stable@vger.kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/api.c')
-rw-r--r--crypto/api.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/crypto/api.c b/crypto/api.c
index 7d71a9b10e5f..edcf690800d4 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -333,12 +333,13 @@ static unsigned int crypto_ctxsize(struct crypto_alg *alg, u32 type, u32 mask)
return len;
}
-static void crypto_shoot_alg(struct crypto_alg *alg)
+void crypto_shoot_alg(struct crypto_alg *alg)
{
down_write(&crypto_alg_sem);
alg->cra_flags |= CRYPTO_ALG_DYING;
up_write(&crypto_alg_sem);
}
+EXPORT_SYMBOL_GPL(crypto_shoot_alg);
struct crypto_tfm *__crypto_alloc_tfm(struct crypto_alg *alg, u32 type,
u32 mask)