crypto: api - Use work queue in crypto_destroy_instance

[ Upstream commit 9ae4577bc077a7e32c3c7d442c95bc76865c0f17 ]

The function crypto_drop_spawn expects to be called in process
context.  However, when an instance is unregistered while it still
has active users, the last user may cause the instance to be freed
in atomic context.

Fix this by delaying the freeing to a work queue.

Fixes: 6bfd48096ff8 ("[CRYPTO] api: Added spawns")
Reported-by: Florent Revest <revest@chromium.org>
Reported-by: syzbot+d769eed29cc42d75e2a3@syzkaller.appspotmail.com
Reported-by: syzbot+610ec0671f51e838436e@syzkaller.appspotmail.com
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Florent Revest <revest@chromium.org>
Acked-by: Florent Revest <revest@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 8c3a869..5dc9ccd 100644 (file)
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -17,6 +17,7 @@
 #include <linux/rtnetlink.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/workqueue.h>
 
 #include "internal.h"
 
@@ -74,15 +75,26 @@ static void crypto_free_instance(struct crypto_instance *inst)
        inst->alg.cra_type->free(inst);
 }
 
-static void crypto_destroy_instance(struct crypto_alg *alg)
+static void crypto_destroy_instance_workfn(struct work_struct *w)
 {
-       struct crypto_instance *inst = (void *)alg;
+       struct crypto_instance *inst = container_of(w, struct crypto_instance,
+                                                   free_work);
        struct crypto_template *tmpl = inst->tmpl;
 
        crypto_free_instance(inst);
        crypto_tmpl_put(tmpl);
 }
 
+static void crypto_destroy_instance(struct crypto_alg *alg)
+{
+       struct crypto_instance *inst = container_of(alg,
+                                                   struct crypto_instance,
+                                                   alg);
+
+       INIT_WORK(&inst->free_work, crypto_destroy_instance_workfn);
+       schedule_work(&inst->free_work);
+}
+
 /*
  * This function adds a spawn to the list secondary_spawns which
  * will be used at the end of crypto_remove_spawns to unregister

diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 224b860..939a319 100644 (file)
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -12,6 +12,7 @@
 #include <linux/kconfig.h>
 #include <linux/list.h>
 #include <linux/types.h>
+#include <linux/workqueue.h>
 
 #include <asm/unaligned.h>
 
@@ -60,6 +61,8 @@ struct crypto_instance {
                struct crypto_spawn *spawns;
        };
 
+       struct work_struct free_work;
+
        void *__ctx[] CRYPTO_MINALIGN_ATTR;
 };