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Date:   Tue, 25 May 2021 15:45:39 +0300
From:   Благодаренко Артём 
        <artem.blagodarenko@...il.com>
To:     Wu Guanghao <wuguanghao3@...wei.com>
Cc:     linux-ext4@...r.kernel.org, liuzhiqiang26@...wei.com,
        linfeilong@...wei.com
Subject: Re: [PATCH 10/12] hashmap: change return value type of,
 ext2fs_hashmap_add()



> On 24 May 2021, at 14:25, Wu Guanghao <wuguanghao3@...wei.com> wrote:
> 
> In ext2fs_hashmap_add(), new entry is allocated by calling
> malloc(). If malloc() return NULL, it will cause a
> segmentation fault problem.
> 
> Here, we change return value type of ext2fs_hashmap_add()
> from void to int. If allocating new entry fails, we will
> return 1, and the callers should also verify the return
> value of ext2fs_hashmap_add().
> 
> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@...wei.com>
> Signed-off-by: Wu Guanghao <wuguanghao3@...wei.com>
> ---
> contrib/android/base_fs.c | 12 +++++++++---
> lib/ext2fs/fileio.c       | 11 +++++++++--
> lib/ext2fs/hashmap.c      | 12 ++++++++++--
> lib/ext2fs/hashmap.h      |  4 ++--
> 4 files changed, 30 insertions(+), 9 deletions(-)
> 
> diff --git a/contrib/android/base_fs.c b/contrib/android/base_fs.c
> index 652317e2..d3e00d18 100644
> --- a/contrib/android/base_fs.c
> +++ b/contrib/android/base_fs.c
> @@ -110,10 +110,16 @@ struct ext2fs_hashmap *basefs_parse(const char *file, const char *mountpoint)
> 	if (!entries)
> 		goto end;
> 
> -	while ((entry = basefs_readline(f, mountpoint, &err)))
> -		ext2fs_hashmap_add(entries, entry, entry->path,
> +	while ((entry = basefs_readline(f, mountpoint, &err))) {
> +		err = ext2fs_hashmap_add(entries, entry, entry->path,
> 				   strlen(entry->path));
> -
> +		if (err) {
> +			free_base_fs_entry(entry);
> +			fclose(f);
> +			ext2fs_hashmap_free(entries);
> +			return NULL;
> +		}
> +	}
> 	if (err) {
> 		fclose(f);
> 		ext2fs_hashmap_free(entries);
> diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
> index a0b5d971..b86951d9 100644
> --- a/lib/ext2fs/fileio.c
> +++ b/lib/ext2fs/fileio.c
> @@ -475,8 +475,15 @@ errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
> 
> 			if (new_block) {
> 				new_block->physblock = file->physblock;
> -				ext2fs_hashmap_add(fs->block_sha_map, new_block,
> -					new_block->sha, sizeof(new_block->sha));
> +				int ret = ext2fs_hashmap_add(fs->block_sha_map,
> +						new_block, new_block->sha,
> +						sizeof(new_block->sha));
> +				if (ret) {
> +					retval = EXT2_ET_NO_MEMORY;
> +					free(new_block);
> +					new_block = NULL;

There is no need to set new_block to NULL here.. new_block is a local variable and the function returns after "fail" label.
Same for blocks above which also jump to the “fail” label.
> +					goto fail;
> +				}
> 			}
> 
> 			if (bmap_flags & BMAP_SET) {
> diff --git a/lib/ext2fs/hashmap.c b/lib/ext2fs/hashmap.c
> index ffe61ce9..7278edaf 100644
> --- a/lib/ext2fs/hashmap.c
> +++ b/lib/ext2fs/hashmap.c
> @@ -36,6 +36,9 @@ struct ext2fs_hashmap *ext2fs_hashmap_create(
> {
> 	struct ext2fs_hashmap *h = calloc(sizeof(struct ext2fs_hashmap) +
> 				sizeof(struct ext2fs_hashmap_entry) * size, 1);
> +	if (!h)
> +		return NULL;
> +
> 	h->size = size;
> 	h->free = free_fct;
> 	h->hash = hash_fct;
> @@ -43,12 +46,15 @@ struct ext2fs_hashmap *ext2fs_hashmap_create(
> 	return h;
> }
> 
> -void ext2fs_hashmap_add(struct ext2fs_hashmap *h, void *data, const void *key,
> -			size_t key_len)
> +int ext2fs_hashmap_add(struct ext2fs_hashmap *h,
> +		void *data, const void *key, size_t key_len)
> {
> 	uint32_t hash = h->hash(key, key_len) % h->size;
> 	struct ext2fs_hashmap_entry *e = malloc(sizeof(*e));
> 
> +	if (!e)
> +		return -1;
> +
> 	e->data = data;
> 	e->key = key;
> 	e->key_len = key_len;
> @@ -62,6 +68,8 @@ void ext2fs_hashmap_add(struct ext2fs_hashmap *h, void *data, const void *key,
> 	h->first = e;
> 	if (!h->last)
> 		h->last = e;
> +
> +	return 0;
> }
> 
> void *ext2fs_hashmap_lookup(struct ext2fs_hashmap *h, const void *key,
> diff --git a/lib/ext2fs/hashmap.h b/lib/ext2fs/hashmap.h
> index dcfa7455..0c09d2bd 100644
> --- a/lib/ext2fs/hashmap.h
> +++ b/lib/ext2fs/hashmap.h
> @@ -27,8 +27,8 @@ struct ext2fs_hashmap_entry {
> struct ext2fs_hashmap *ext2fs_hashmap_create(
> 				uint32_t(*hash_fct)(const void*, size_t),
> 				void(*free_fct)(void*), size_t size);
> -void ext2fs_hashmap_add(struct ext2fs_hashmap *h, void *data, const void *key,
> -			size_t key_len);
> +int ext2fs_hashmap_add(struct ext2fs_hashmap *h,
> +		       void *data, const void *key,size_t key_len);
> void *ext2fs_hashmap_lookup(struct ext2fs_hashmap *h, const void *key,
> 			    size_t key_len);
> void *ext2fs_hashmap_iter_in_order(struct ext2fs_hashmap *h,
> -- 

Best regards,
Artem Blagodarenko

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