Re: [PATCH] ecryptfs: replace ecryptfs_from_hex() with hex2bin()

[DRIF ABDELMALEK MOHAMED SAID]

Gentle ping on this one — seems to have gotten buried during the merge window.

Thanks,

On Sat, Aug 29, 2026 at 8:45 PM Drif Abdelmalek Mohamed Said
<drifabdelmalekmohamedsaid@xxxxxxxxx> wrote:
>
> ecryptfs_from_hex() relied on the deprecated simple_strtoul(). Rather
> than patching it to use kstrtoul(), its intended replacement, remove it
> entirely and switch all call sites to the generic hex2bin() helper
> from <linux/hex.h>, which already provides the same functionality.
>
> Update call sites with the (u8 *) casts required by hex2bin()'s
> signature.
>
> All call sites guarantee src is composed only of valid hex characters
> and that src is at least 2*dst_size bytes, so hex2bin()'s stricter
> error handling is never triggered here.
>
> Signed-off-by: Drif Abdelmalek Mohamed Said <drifabdelmalekmohamedsaid@xxxxxxxxx>
> ---
>  fs/ecryptfs/crypto.c          | 18 ------------------
>  fs/ecryptfs/ecryptfs_kernel.h |  1 -
>  fs/ecryptfs/keystore.c        |  7 ++++---
>  3 files changed, 4 insertions(+), 22 deletions(-)
>
> diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
> index e67119b6029c..7e802fd631a6 100644
> --- a/fs/ecryptfs/crypto.c
> +++ b/fs/ecryptfs/crypto.c
> @@ -29,24 +29,6 @@
>  #define DECRYPT                0
>  #define ENCRYPT                1
>
> -/**
> - * ecryptfs_from_hex
> - * @dst: Buffer to take the bytes from src hex; must be at least of
> - *       size (src_size / 2)
> - * @src: Buffer to be converted from a hex string representation to raw value
> - * @dst_size: size of dst buffer, or number of hex characters pairs to convert
> - */
> -void ecryptfs_from_hex(char *dst, char *src, int dst_size)
> -{
> -       int x;
> -       char tmp[3] = { 0, };
> -
> -       for (x = 0; x < dst_size; x++) {
> -               tmp[0] = src[x * 2];
> -               tmp[1] = src[x * 2 + 1];
> -               dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
> -       }
> -}
>
>  static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
>                                                   const char *cipher_name,
> diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
> index 58165928ed1e..be91f7c3fc58 100644
> --- a/fs/ecryptfs/ecryptfs_kernel.h
> +++ b/fs/ecryptfs/ecryptfs_kernel.h
> @@ -47,7 +47,6 @@ ecryptfs_to_hex(char *dst, char *src, size_t src_size)
>         *end = '\0';
>  }
>
> -extern void ecryptfs_from_hex(char *dst, char *src, int dst_size);
>
>  struct ecryptfs_key_record {
>         unsigned char type;
> diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
> index 51651314b7a6..dcfb2e5fa88e 100644
> --- a/fs/ecryptfs/keystore.c
> +++ b/fs/ecryptfs/keystore.c
> @@ -18,6 +18,7 @@
>  #include <linux/random.h>
>  #include <linux/scatterlist.h>
>  #include <linux/slab.h>
> +#include <linux/hex.h>
>  #include "ecryptfs_kernel.h"
>
>  /*
> @@ -713,7 +714,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
>                 goto out_free_unlock;
>         }
>         s->i += s->packet_size_len;
> -       ecryptfs_from_hex(&dest[s->i],
> +       hex2bin((u8 *)&dest[s->i],
>                           mount_crypt_stat->global_default_fnek_sig,
>                           ECRYPTFS_SIG_SIZE);
>         s->i += ECRYPTFS_SIG_SIZE;
> @@ -2015,7 +2016,7 @@ write_tag_1_packet(char *dest, size_t *remaining_bytes,
>         int rc = 0;
>
>         (*packet_size) = 0;
> -       ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
> +       hex2bin((u8 *)key_rec->sig, auth_tok->token.private_key.signature,
>                           ECRYPTFS_SIG_SIZE);
>         encrypted_session_key_valid = 0;
>         for (i = 0; i < crypt_stat->key_size; i++)
> @@ -2179,7 +2180,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
>         int rc = 0;
>
>         (*packet_size) = 0;
> -       ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
> +       hex2bin((u8 *)key_rec->sig, auth_tok->token.password.signature,
>                           ECRYPTFS_SIG_SIZE);
>         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
>                                                         crypt_stat->cipher);
> --
> 2.43.0
>