linux-kernel - [PATCH 3.16 234/346] dm crypt: fix free of bad values after tfm allocation failure

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Message-ID: <lsq.1479082460.537919041@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Eric Biggers" <ebiggers@...gle.com>,
        "Mike Snitzer" <snitzer@...hat.com>
Subject: [PATCH 3.16 234/346] dm crypt: fix free of bad values after tfm
 allocation failure

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@...gle.com>

commit 5d0be84ec0cacfc7a6d6ea548afdd07d481324cd upstream.

If crypt_alloc_tfms() had to allocate multiple tfms and it failed before
the last allocation, then it would call crypt_free_tfms() and could free
pointers from uninitialized memory -- due to the crypt_free_tfms() check
for non-zero cc->tfms[i].  Fix by allocating zeroed memory.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/md/dm-crypt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1400,7 +1400,7 @@ static int crypt_alloc_tfms(struct crypt
 	unsigned i;
 	int err;
 
-	cc->tfms = kmalloc(cc->tfms_count * sizeof(struct crypto_ablkcipher *),
+	cc->tfms = kzalloc(cc->tfms_count * sizeof(struct crypto_ablkcipher *),
 			   GFP_KERNEL);
 	if (!cc->tfms)
 		return -ENOMEM;