[PATCH 06/17] fs/squashfs: sqfs_read_directory_table: fix memory leak

Miquel Raynal
2020-10-15T13:54:12Z

Hi Richard,

Richard Genoud <richard.genoud@posteo.net> wrote on Wed, 14 Oct 2020
10:06:11 +0200:

> pos_list wasn't freed on every error
>
> Signed-off-by: Richard Genoud <richard.genoud@posteo.net>

Same comment here (and probably after as well) as in patch 05/17, not
sure this is actually relevant for the community but I prefer this:

bar = malloc();
...
if (ret)
goto free_bar;

foo = malloc();
...
if (ret)
goto free foo;

...

foo:
kfree(foo);
bar:
kfree(bar);

than:

foo = NULL;
bar = NULL;

...
if (ret)
goto out;
...
if (ret)
goto out;
...
out:
if (ret)
kfree(...)

> ---
> fs/squashfs/sqfs.c | 31 +++++++++++++++++--------------
> 1 file changed, 17 insertions(+), 14 deletions(-)
>
> diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c
> index 55d183663a8..c4d74fd4d6d 100644
> --- a/fs/squashfs/sqfs.c
> +++ b/fs/squashfs/sqfs.c
> @@ -722,6 +722,8 @@ static int sqfs_read_directory_table(unsigned char **dir_table, u32 **pos_list)
> unsigned long dest_len = 0;
> bool compressed;
>
> + *dir_table = NULL;
> + *pos_list = NULL;
> /* DIRECTORY TABLE */
> table_size = get_unaligned_le64(&sblk->fragment_table_start) -
> get_unaligned_le64(&sblk->directory_table_start);
> @@ -736,35 +738,31 @@ static int sqfs_read_directory_table(unsigned char **dir_table, u32 **pos_list)
> return -ENOMEM;
>
> if (sqfs_disk_read(start, n_blks, dtb) < 0)
> - goto free_dtb;
> + goto out;
>
> /* Parse directory table (metadata block) header */
> ret = sqfs_read_metablock(dtb, table_offset, &compressed, &src_len);
> if (ret)
> - goto free_dtb;
> + goto out;
>
> /* Calculate total size to store the whole decompressed table */
> metablks_count = sqfs_count_metablks(dtb, table_offset, table_size);
> if (metablks_count < 1)
> - goto free_dtb;
> + goto out;
>
> *dir_table = malloc(metablks_count * SQFS_METADATA_BLOCK_SIZE);
> if (!*dir_table)
> - goto free_dtb;
> + goto out;
>
> *pos_list = malloc(metablks_count * sizeof(u32));
> - if (!*pos_list) {
> - free(*dir_table);
> - goto free_dtb;
> - }
> + if (!*pos_list)
> + goto out;
>
> ret = sqfs_get_metablk_pos(*pos_list, dtb, table_offset,
> metablks_count);
> if (ret) {
> metablks_count = -1;
> - free(*dir_table);
> - free(*pos_list);
> - goto free_dtb;
> + goto out;
> }
>
> src_table = dtb + table_offset + SQFS_HEADER_SIZE;
> @@ -780,8 +778,7 @@ static int sqfs_read_directory_table(unsigned char **dir_table, u32 **pos_list)
> &dest_len, src_table, src_len);
> if (ret) {
> metablks_count = -1;
> - free(*dir_table);
> - goto free_dtb;
> + goto out;
> }
>
> if (dest_len < SQFS_METADATA_BLOCK_SIZE) {
> @@ -803,7 +800,13 @@ static int sqfs_read_directory_table(unsigned char **dir_table, u32 **pos_list)
> src_table += src_len + SQFS_HEADER_SIZE;
> }
>
> -free_dtb:
> +out:
> + if (metablks_count < 1) {
> + free(*dir_table);
> + free(*pos_list);
> + *dir_table = NULL;
> + *pos_list = NULL;
> + }
> free(dtb);
>
> return metablks_count;

Thanks,
Miqu?l