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| author | Eric Biggers <ebiggers@google.com> | 2020-06-04 11:52:53 -0700 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2020-06-15 17:38:54 +1000 |
| commit | 77251e41f89a813b4090f5199442f217bbf11297 (patch) | |
| tree | f29d1c0c6779eaea7dd62b465e653d713415a132 /crypto | |
| parent | 24c7bf089453f6a1eed4c77ed0604bf4bb8cfb03 (diff) | |
| download | linux-77251e41f89a813b4090f5199442f217bbf11297.tar.gz linux-77251e41f89a813b4090f5199442f217bbf11297.tar.bz2 linux-77251e41f89a813b4090f5199442f217bbf11297.zip | |
crypto: algboss - don't wait during notifier callback
When a crypto template needs to be instantiated, CRYPTO_MSG_ALG_REQUEST
is sent to crypto_chain. cryptomgr_schedule_probe() handles this by
starting a thread to instantiate the template, then waiting for this
thread to complete via crypto_larval::completion.
This can deadlock because instantiating the template may require loading
modules, and this (apparently depending on userspace) may need to wait
for the crc-t10dif module (lib/crc-t10dif.c) to be loaded. But
crc-t10dif's module_init function uses crypto_register_notifier() and
therefore takes crypto_chain.rwsem for write. That can't proceed until
the notifier callback has finished, as it holds this semaphore for read.
Fix this by removing the wait on crypto_larval::completion from within
cryptomgr_schedule_probe(). It's actually unnecessary because
crypto_alg_mod_lookup() calls crypto_larval_wait() itself after sending
CRYPTO_MSG_ALG_REQUEST.
This only actually became a problem in v4.20 due to commit b76377543b73
("crc-t10dif: Pick better transform if one becomes available"), but the
unnecessary wait was much older.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207159
Reported-by: Mike Gerow <gerow@google.com>
Fixes: 398710379f51 ("crypto: algapi - Move larval completion into algboss")
Cc: <stable@vger.kernel.org> # v3.6+
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reported-by: Kai Lüke <kai@kinvolk.io>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/algboss.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/crypto/algboss.c b/crypto/algboss.c index 535f1f87e6c1..5ebccbd6b74e 100644 --- a/crypto/algboss.c +++ b/crypto/algboss.c @@ -178,8 +178,6 @@ static int cryptomgr_schedule_probe(struct crypto_larval *larval) if (IS_ERR(thread)) goto err_put_larval; - wait_for_completion_interruptible(&larval->completion); - return NOTIFY_STOP; err_put_larval: |