crypto: caam - fix use-after-free KASAN issue for HASH algorithms

Here's the KASAN report:
BUG: KASAN: use-after-free in ahash_done+0xdc/0x3b8
Read of size 1 at addr ffff00002303f010 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc1-00162-gfcb90d5 #59
Hardware name: LS1046A RDB Board (DT)
Call trace:
dump_backtrace+0x0/0x260
show_stack+0x14/0x20
dump_stack+0xe8/0x144
print_address_description.isra.11+0x64/0x348
__kasan_report+0x11c/0x230
kasan_report+0xc/0x18
__asan_load1+0x5c/0x68
ahash_done+0xdc/0x3b8
caam_jr_dequeue+0x390/0x608
tasklet_action_common.isra.13+0x1ec/0x230
tasklet_action+0x24/0x30
efi_header_end+0x1a4/0x370
irq_exit+0x114/0x128
__handle_domain_irq+0x80/0xe0
gic_handle_irq+0x50/0xa0
el1_irq+0xb8/0x180
cpuidle_enter_state+0xa4/0x490
cpuidle_enter+0x48/0x70
call_cpuidle+0x44/0x70
do_idle+0x304/0x338
cpu_startup_entry+0x24/0x40
rest_init+0xf8/0x10c
arch_call_rest_init+0xc/0x14
start_kernel+0x774/0x7b4

Allocated by task 263:
save_stack+0x24/0xb0
__kasan_kmalloc.isra.10+0xc4/0xe0
kasan_kmalloc+0xc/0x18
__kmalloc+0x178/0x2b8
ahash_edesc_alloc+0x58/0x1f8
ahash_final_no_ctx+0x94/0x6e8
ahash_final+0x24/0x30
crypto_ahash_op+0x58/0xb0
crypto_ahash_final+0x30/0x40
do_ahash_op+0x2c/0xa0
test_ahash_vec_cfg+0x894/0x9e0
test_hash_vec_cfg+0x6c/0x88
test_hash_vec+0xfc/0x1e0
__alg_test_hash+0x1ac/0x368
alg_test_hash+0xf8/0x1c8
alg_test.part.44+0x114/0x4a0
alg_test+0x1c/0x60
cryptomgr_test+0x34/0x58
kthread+0x1b8/0x1c0
ret_from_fork+0x10/0x18

Freed by task 0:
save_stack+0x24/0xb0
__kasan_slab_free+0x10c/0x188
kasan_slab_free+0x10/0x18
kfree+0x7c/0x298
ahash_done+0xd4/0x3b8
caam_jr_dequeue+0x390/0x608
tasklet_action_common.isra.13+0x1ec/0x230
tasklet_action+0x24/0x30
efi_header_end+0x1a4/0x370

The buggy address belongs to the object at ffff00002303f000
which belongs to the cache dma-kmalloc-128 of size 128
The buggy address is located 16 bytes inside of
128-byte region [ffff00002303f000, ffff00002303f080)
The buggy address belongs to the page:
page:fffffe00006c0fc0 refcount:1 mapcount:0 mapping:ffff00093200c000 index:0x0
flags: 0xffff00000000200(slab)
raw: 0ffff00000000200 dead000000000100 dead000000000122 ffff00093200c000
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff00002303ef00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff00002303ef80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff00002303f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff00002303f080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff00002303f100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Fixes: 21b014f038d3 ("crypto: caam - add crypto_engine support for HASH algorithms")
Signed-off-by: Iuliana Prodan <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/caam/caamhash.c

···
 	struct caam_hash_state *state = ahash_request_ctx(req);
 	struct caam_hash_ctx *ctx = crypto_ahash_ctx(ahash);
 	int ecode = 0;
+	bool has_bklog;
 
 	dev_dbg(jrdev, "%s %d: err 0x%x\n", __func__, __LINE__, err);
 
 	edesc = state->edesc;
+	has_bklog = edesc->bklog;
 
 	if (err)
 		ecode = caam_jr_strstatus(jrdev, err);
···
 	 * If no backlog flag, the completion of the request is done
 	 * by CAAM, not crypto engine.
 	 */
-	if (!edesc->bklog)
+	if (!has_bklog)
 		req->base.complete(&req->base, ecode);
 	else
 		crypto_finalize_hash_request(jrp->engine, req, ecode);
···
 	struct caam_hash_state *state = ahash_request_ctx(req);
 	int digestsize = crypto_ahash_digestsize(ahash);
 	int ecode = 0;
+	bool has_bklog;
 
 	dev_dbg(jrdev, "%s %d: err 0x%x\n", __func__, __LINE__, err);
 
 	edesc = state->edesc;
+	has_bklog = edesc->bklog;
 	if (err)
 		ecode = caam_jr_strstatus(jrdev, err);
 
···
 	 * If no backlog flag, the completion of the request is done
 	 * by CAAM, not crypto engine.
 	 */
-	if (!edesc->bklog)
+	if (!has_bklog)
 		req->base.complete(&req->base, ecode);
 	else
 		crypto_finalize_hash_request(jrp->engine, req, ecode);