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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2018-03-16 08:21:08 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-16 15:40:19 +0100 |
| commit | 225b3dc92da1a3198cf687b13435fef952757a8f (patch) | |
| tree | afea7f22d030ab0a6dead88cbb22fdc5d2b1019c /drivers/usb/wusbcore | |
| parent | 7bb9aedac66cc768b255e60f97a137935dd818d8 (diff) | |
| download | linux-225b3dc92da1a3198cf687b13435fef952757a8f.tar.bz2 | |
USB: wusbcore: crypto: Remove VLA usage
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
Notice that in this particular case, an alternative to kzalloc is kcalloc,
in which case the code would look as follows instead:
iv = kcalloc(crypto_skcipher_ivsize(tfm_cbc), sizeof(*iv), GFP_KERNEL);
but if the data type of _iv_ never changes, or the type size is always one
byte, kzalloc is good enough.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/wusbcore')
| -rw-r--r-- | drivers/usb/wusbcore/crypto.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/usb/wusbcore/crypto.c b/drivers/usb/wusbcore/crypto.c index 4c00be2d1993..aff50eb09ca9 100644 --- a/drivers/usb/wusbcore/crypto.c +++ b/drivers/usb/wusbcore/crypto.c @@ -202,7 +202,7 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc, struct scatterlist sg[4], sg_dst; void *dst_buf; size_t dst_size; - u8 iv[crypto_skcipher_ivsize(tfm_cbc)]; + u8 *iv; size_t zero_padding; /* @@ -224,7 +224,9 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc, if (!dst_buf) goto error_dst_buf; - memset(iv, 0, sizeof(iv)); + iv = kzalloc(crypto_skcipher_ivsize(tfm_cbc), GFP_KERNEL); + if (!iv) + goto error_iv; /* Setup B0 */ scratch->b0.flags = 0x59; /* Format B0 */ @@ -276,6 +278,8 @@ static int wusb_ccm_mac(struct crypto_skcipher *tfm_cbc, bytewise_xor(mic, &scratch->ax, iv, 8); result = 8; error_cbc_crypt: + kfree(iv); +error_iv: kfree(dst_buf); error_dst_buf: return result; |