linux-kernel - [PATCH] crypto: Mark tfm buffer as non leak.

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Date:   Thu, 3 Sep 2020 15:40:07 +0200
From:   Peter Enderborg <peter.enderborg@...y.com>
To:     <linux-crypto@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>
CC:     Peter Enderborg <peter.enderborg@...y.com>
Subject: [PATCH] crypto: Mark tfm buffer as non leak.

When running kmemleak on this I got a lot of

unreferenced object 0xfffffff942d4ec00 (size 1024):
  comm "init", pid 1, jiffies 4294893619 (age 17475.864s)
  hex dump (first 32 bytes):
    38 1d cf bd 9e ff ff ff b8 37 8b bd 9e ff ff ff  8........7......
    78 38 8b bd 9e ff ff ff 10 00 00 00 00 00 00 00  x8..............
  backtrace:
    [<00000000c3c55a80>] __kmalloc+0x2cc/0x3b0
    [<00000000c599b091>] crypto_create_tfm+0x38/0xf0
    [<00000000d4516e51>] crypto_spawn_tfm2+0x58/0xa0
    [<000000001bab58aa>] cryptd_skcipher_init_tfm+0x1c/0x40
    [<0000000006748df3>] crypto_skcipher_init_tfm+0x158/0x1e0
    [<0000000017f3270c>] crypto_create_tfm+0x54/0xf0
    [<000000006af1de62>] crypto_alloc_tfm+0x88/0x198
    [<000000000d8e8c03>] crypto_alloc_skcipher+0x1c/0x28
    [<0000000085448a2a>] cryptd_alloc_skcipher+0x5c/0xb0
    [<000000003c48c083>] simd_skcipher_init+0x24/0x68
    [<0000000006748df3>] crypto_skcipher_init_tfm+0x158/0x1e0
    [<0000000017f3270c>] crypto_create_tfm+0x54/0xf0
    [<00000000d4516e51>] crypto_spawn_tfm2+0x58/0xa0
    [<00000000b5344705>] crypto_cts_init_tfm+0x1c/0x68
    [<0000000006748df3>] crypto_skcipher_init_tfm+0x158/0x1e0
    [<0000000017f3270c>] crypto_create_tfm+0x54/0xf0

This is caused by tfm = (struct crypto_tfm *)(mem + tfmsize);
that is keept instead of the allocated buffer in mem.
Reference counting is done on alg.

Signed-off-by: Peter Enderborg <peter.enderborg@...y.com>
---
 crypto/api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/api.c b/crypto/api.c
index ed08cbd5b9d3..1a9cb6852a56 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -21,6 +21,7 @@
 #include <linux/string.h>
 #include <linux/completion.h>
 #include "internal.h"
+#include <linux/kmemleak.h>
 
 LIST_HEAD(crypto_alg_list);
 EXPORT_SYMBOL_GPL(crypto_alg_list);
@@ -460,7 +461,7 @@ void *crypto_create_tfm_node(struct crypto_alg *alg,
 
 	if (!tfm->exit && alg->cra_init && (err = alg->cra_init(tfm)))
 		goto cra_init_failed;
-
+	kmemleak_not_leak(mem);
 	goto out;
 
 cra_init_failed:
-- 
2.17.1