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SubjectRE: [PATCH 1/2] exfat: add dir-entry set checksum validation
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> Add checksum validation for dir-entry set when getting it.
> exfat_calc_dir_chksum_with_entry_set() also validates entry-type.
>
> ** This patch depends on:
> '[PATCH v3] exfat: integrates dir-entry getting and validation'
>
> Signed-off-by: Tetsuhiro Kohada <kohada.t2@gmail.com>
> ---
> fs/exfat/dir.c | 34 ++++++++++++++++++++++------------
> 1 file changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index c9715c7a55a1..2e79ac464f5f 100644
> --- a/fs/exfat/dir.c
> +++ b/fs/exfat/dir.c
> @@ -563,18 +563,27 @@ int exfat_remove_entries(struct inode *inode, struct exfat_chain *p_dir,
> return 0;
> }
>
> -void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
> +static int exfat_calc_dir_chksum_with_entry_set(struct
> +exfat_entry_set_cache *es, u16 *chksum)
> {
> - int chksum_type = CS_DIR_ENTRY, i;
> - unsigned short chksum = 0;
> struct exfat_dentry *ep;
> + int i;
>
> - for (i = 0; i < es->num_entries; i++) {
> - ep = exfat_get_validated_dentry(es, i, TYPE_ALL);
> - chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
> - chksum_type);
> - chksum_type = CS_DEFAULT;
> + ep = container_of(es->de_file, struct exfat_dentry, dentry.file);
> + *chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, 0, CS_DIR_ENTRY);
> + for (i = 0; i < es->de_file->num_ext; i++) {
> + ep = exfat_get_validated_dentry(es, 1 + i, TYPE_SECONDARY);
> + if (!ep)
> + return -EIO;
> + *chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, *chksum, CS_DEFAULT);
> }
> + return 0;
We can return checksum after removing u16 *chksum argument.
> +}
> +
> +void exfat_update_dir_chksum_with_entry_set(struct
> +exfat_entry_set_cache *es) {
> + u16 chksum;
> +
> + exfat_calc_dir_chksum_with_entry_set(es, &chksum);
> es->de_file->checksum = cpu_to_le16(chksum);
> es->modified = true;
> }
> @@ -775,6 +784,7 @@ struct exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
> struct exfat_entry_set_cache *es;
> struct exfat_dentry *ep;
> struct buffer_head *bh;
> + u16 chksum;
>
> if (p_dir->dir == DIR_DELETED) {
> exfat_err(sb, "access to deleted dentry"); @@ -839,10 +849,10 @@ struct
> exfat_entry_set_cache *exfat_get_dentry_set(struct super_block *sb,
> goto free_es;
> es->de_stream = &ep->dentry.stream;
>
> - for (i = 2; i < es->num_entries; i++) {
> - if (!exfat_get_validated_dentry(es, i, TYPE_SECONDARY))
> - goto free_es;
> - }
> + if (max_entries == ES_ALL_ENTRIES &&
> + ((exfat_calc_dir_chksum_with_entry_set(es, &chksum) ||
> + chksum != le16_to_cpu(es->de_file->checksum))))
Please add error print log if checksum mismatch error happen.
> + goto free_es;
>
> return es;
>
> --
> 2.25.1


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