[PATCH v2 2/4] crypto: caam - fix use-after-free KASAN issue for AEAD algorithms

From: Iuliana Prodan
Date: Mon Apr 06 2020 - 18:47:49 EST


Here's the KASAN report:
BUG: KASAN: use-after-free in aead_crypt_done+0x60/0xd8
Read of size 1 at addr ffff00002303f014 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc1-00162-gfcb90d5 #58
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
aead_crypt_done+0x60/0xd8
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
_raw_spin_unlock_irq+0x2c/0x78
finish_task_switch+0xa4/0x2f8
__schedule+0x3a4/0x890
schedule_idle+0x28/0x50
do_idle+0x22c/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
aead_edesc_alloc+0x1b4/0xbf0
ipsec_gcm_encrypt+0xd4/0x140
crypto_aead_encrypt+0x50/0x68
test_aead_vec_cfg+0x498/0xec0
test_aead_vec+0x110/0x200
alg_test_aead+0xfc/0x680
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
aead_crypt_done+0x58/0xd8
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 20 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: 1c2402266713 ("crypto: caam - add crypto_engine support for AEAD algorithms")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.6
Signed-off-by: Iuliana Prodan <iuliana.prodan@xxxxxxx>
---
drivers/crypto/caam/caamalg.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
index 86be876..4174bd9 100644
--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -963,10 +963,12 @@ static void aead_crypt_done(struct device *jrdev, u32 *desc, u32 err,
struct caam_drv_private_jr *jrp = dev_get_drvdata(jrdev);
struct aead_edesc *edesc;
int ecode = 0;
+ bool has_bklog;

dev_dbg(jrdev, "%s %d: err 0x%x\n", __func__, __LINE__, err);

edesc = rctx->edesc;
+ has_bklog = edesc->bklog;

if (err)
ecode = caam_jr_strstatus(jrdev, err);
@@ -979,7 +981,7 @@ static void aead_crypt_done(struct device *jrdev, u32 *desc, u32 err,
* If no backlog flag, the completion of the request is done
* by CAAM, not crypto engine.
*/
- if (!edesc->bklog)
+ if (!has_bklog)
aead_request_complete(req, ecode);
else
crypto_finalize_aead_request(jrp->engine, req, ecode);
--
2.1.0