[PATCH 1/4] crypto: caam - fix use-after-free KASAN issue for SKCIPHER algorithms

[Iuliana Prodan]

Here's the KASAN report:
BUG: KASAN: use-after-free in skcipher_crypt_done+0xe8/0x1a8
Read of size 1 at addr ffff00002304001c by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc1-00162-gfcb90d5 #9
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
 skcipher_crypt_done+0xe8/0x1a8
 caam_jr_dequeue+0x390/0x608
 tasklet_action_common.isra.13+0x1ec/0x230
 ...

Fixes: ee38767f152a ("crypto: caam - support crypto_engine framework for SKCIPHER algorithms")
Signed-off-by: Iuliana Prodan <iuliana.prodan@xxxxxxx>
---
 drivers/crypto/caam/caamalg.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
index b7bb7c3..5538539 100644
--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -1022,8 +1022,6 @@ static void skcipher_crypt_done(struct device *jrdev, u32 *desc, u32 err,
 		     DUMP_PREFIX_ADDRESS, 16, 4, req->dst,
 		     edesc->dst_nents > 1 ? 100 : req->cryptlen, 1);
 
-	kfree(edesc);
-
 	/*
 	 * If no backlog flag, the completion of the request is done
 	 * by CAAM, not crypto engine.
@@ -1032,6 +1030,8 @@ static void skcipher_crypt_done(struct device *jrdev, u32 *desc, u32 err,
 		skcipher_request_complete(req, ecode);
 	else
 		crypto_finalize_skcipher_request(jrp->engine, req, ecode);
+
+	kfree(edesc);
 }
 
 /*
-- 
2.1.0