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| author |   Herbert Xu <herbert@gondor.apana.org.au> | 2020-04-10 16:09:42 +1000 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2020-04-16 16:49:22 +1000 |
| commit | 6603523bf5e432c7c8490fb500793bb15d4e5f61 (patch) | |
| tree | a55f489fb787cdc482819bcf29a1a0327549637e /crypto/api.c | |
| parent | crypto: ccp -- don't "select" CONFIG_DMADEVICES (diff) | |
| download | linux-dev-6603523bf5e432c7c8490fb500793bb15d4e5f61.tar.xz linux-dev-6603523bf5e432c7c8490fb500793bb15d4e5f61.zip | |
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.c | 3 |
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) |