On Thu, Dec 26, 2024 at 10:30:49PM +0530, Atharva Tiwari wrote:
> The `vmac_update` function previously assumed that `p` was aligned,
> which could lead to misaligned memory accesses when processing blocks.
> This patch resolves the issue by,
> introducing a temporary buffer to ensure alignment.
>
> Changes include:
> - Allocating a temporary buffer (`__le64 *data`) to store aligned blocks.
> - Using `get_unaligned_le64` to safely read data into the temporary buffer.
> - Iteratively processing blocks with the `vhash_blocks` function.
> - Properly freeing the allocated temporary buffer after processing.
>
> Signed-off-by: Atharva Tiwari <evepolonium@xxxxxxxxx>
> ---
> crypto/vmac.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/crypto/vmac.c b/crypto/vmac.c
> index 2ea384645ecf..513fbd5bc581 100644
> --- a/crypto/vmac.c
> +++ b/crypto/vmac.c
> @@ -518,9 +518,19 @@ static int vmac_update(struct shash_desc *desc, const u8 *p, unsigned int len)
>
> if (len >= VMAC_NHBYTES) {
> n = round_down(len, VMAC_NHBYTES);
> - /* TODO: 'p' may be misaligned here */
> - vhash_blocks(tctx, dctx, (const __le64 *)p, n / VMAC_NHBYTES);
> - p += n;
> + const u8 *end = p + n;
> + const uint16_t num_blocks = VMAC_NHBYTES/sizeof(__le64);
> + __le64 *data = kmalloc(num_blocks * sizeof(__le64), GFP_KERNEL);
> +
> + while (p < end) {
> + for (unsigned short i = 0; i < num_blocks; i++) {
> + data[i] = get_unaligned_le64(p + i * sizeof(__le64));
> + }
This is not what I meant by using get_unaligned_le64. I meant
replacing the actual 64-bit accesses within vhash_blocks with
get_unaligned_le64.
Cheers,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
