Commit 9ae4577b authored by Herbert Xu's avatar Herbert Xu
Browse files

crypto: api - Use work queue in crypto_destroy_instance 



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: 6bfd4809 ("[CRYPTO] api: Added spawns")
Reported-by: default avatarFlorent Revest <revest@chromium.org>
Reported-by: default avatar <syzbot+d769eed29cc42d75e2a3@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+610ec0671f51e838436e@syzkaller.appspotmail.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Tested-by: default avatarFlorent Revest <revest@chromium.org>
Acked-by: default avatarFlorent Revest <revest@chromium.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 7999b615

crypto/algapi.c

+14 −2
Original line number Diff line number Diff line
@@ -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

include/crypto/algapi.h

+3 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/cache.h>

#include <linux/crypto.h>

#include <linux/types.h>

#include <linux/workqueue.h>



/*

 * Maximum values for blocksize and alignmask, used to allocate
@@ -82,6 +83,8 @@ struct crypto_instance { 
		struct crypto_spawn *spawns;

	};



	struct work_struct free_work;



	void *__ctx[] CRYPTO_MINALIGN_ATTR;

};