[PATCH v2] Bluetooth: Remove VLA usage in aes_cmac
flat view
STALE3121d
From: Gustavo A. R. Silva <hidden>
Date: 2018-03-21 01:05:31
Also in:
linux-bluetooth, lkml
Subsystem:
bluetooth subsystem, the rest · Maintainers:
Marcel Holtmann, Luiz Augusto von Dentz, Linus Torvalds
In preparation to enabling -Wvla, remove VLA and replace it with dynamic memory allocation instead. The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug. Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Gustavo A. R. Silva <redacted> --- Changes in v2: - Fix memory leak in previous patch. net/bluetooth/smp.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index a2ddae2..0fa7035 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c@@ -173,7 +173,7 @@ static int aes_cmac(struct crypto_shash *tfm, const u8 k[16], const u8 *m, size_t len, u8 mac[16]) { uint8_t tmp[16], mac_msb[16], msg_msb[CMAC_MSG_MAX]; - SHASH_DESC_ON_STACK(desc, tfm); + struct shash_desc *shash; int err; if (len > CMAC_MSG_MAX)
@@ -184,8 +184,13 @@ static int aes_cmac(struct crypto_shash *tfm, const u8 k[16], const u8 *m, return -EINVAL; } - desc->tfm = tfm; - desc->flags = 0; + shash = kzalloc(sizeof(*shash) + crypto_shash_descsize(tfm), + GFP_KERNEL); + if (!shash) + return -ENOMEM; + + shash->tfm = tfm; + shash->flags = 0; /* Swap key and message from LSB to MSB */ swap_buf(k, tmp, 16);
@@ -197,11 +202,13 @@ static int aes_cmac(struct crypto_shash *tfm, const u8 k[16], const u8 *m, err = crypto_shash_setkey(tfm, tmp, 16); if (err) { BT_ERR("cipher setkey failed: %d", err); + kfree(shash); return err; } - err = crypto_shash_digest(desc, msg_msb, len, mac_msb); - shash_desc_zero(desc); + err = crypto_shash_digest(shash, msg_msb, len, mac_msb); + shash_desc_zero(shash); + kfree(shash); if (err) { BT_ERR("Hash computation error %d", err); return err;
--
2.7.4