Re: [Qemu-devel] [PATCH 09/13] dmg: Fix bdrv_open() error handling

[Blue Swirl]

On Fri, Feb 1, 2013 at 2:28 PM, Stefan Hajnoczi <address@hidden> wrote:
> From: Kevin Wolf <address@hidden>
>
> Return -errno instead of -1 on errors and add error checks in some
> places that didn't have one. Passing things by reference requires more
> correct typing, replaced a few off_ts therefore - with a 32-bit off_t
> this is even a fix for truncation bugs.
>
> While touching the code, fix even some more memory leaks than in the
> other drivers...
>
> Signed-off-by: Kevin Wolf <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
>  block/dmg.c | 135 
> +++++++++++++++++++++++++++++++++++++++++++-----------------
>  1 file changed, 97 insertions(+), 38 deletions(-)
>
> diff --git a/block/dmg.c b/block/dmg.c
> index ac397dc..53be25d 100644
> --- a/block/dmg.c
> +++ b/block/dmg.c
> @@ -57,29 +57,42 @@ static int dmg_probe(const uint8_t *buf, int buf_size, 
> const char *filename)
>      return 0;
>  }
>
> -static off_t read_off(BlockDriverState *bs, int64_t offset)
> +static int read_uint64(BlockDriverState *bs, int64_t offset, uint64_t 
> *result)
>  {
> -       uint64_t buffer;
> -       if (bdrv_pread(bs->file, offset, &buffer, 8) < 8)
> -               return 0;
> -       return be64_to_cpu(buffer);
> +    uint64_t buffer;
> +    int ret;
> +
> +    ret = bdrv_pread(bs->file, offset, &buffer, 8);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    *result = be64_to_cpu(buffer);
> +    return 0;
>  }
>
> -static off_t read_uint32(BlockDriverState *bs, int64_t offset)
> +static int read_uint32(BlockDriverState *bs, int64_t offset, uint32_t 
> *result)
>  {
> -       uint32_t buffer;
> -       if (bdrv_pread(bs->file, offset, &buffer, 4) < 4)
> -               return 0;
> -       return be32_to_cpu(buffer);
> +    uint32_t buffer;
> +    int ret;
> +
> +    ret = bdrv_pread(bs->file, offset, &buffer, 4);
> +    if (ret < 0) {
> +        return ret;
> +    }
> +
> +    *result = be32_to_cpu(buffer);
> +    return 0;
>  }
>
>  static int dmg_open(BlockDriverState *bs, int flags)
>  {
>      BDRVDMGState *s = bs->opaque;
> -    off_t info_begin,info_end,last_in_offset,last_out_offset;
> -    uint32_t count;
> +    uint64_t info_begin,info_end,last_in_offset,last_out_offset;
> +    uint32_t count, tmp;
>      uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
>      int64_t offset;
> +    int ret;
>
>      bs->read_only = 1;
>      s->n_chunks = 0;
> @@ -88,21 +101,32 @@ static int dmg_open(BlockDriverState *bs, int flags)
>      /* read offset of info blocks */
>      offset = bdrv_getlength(bs->file);
>      if (offset < 0) {
> +        ret = offset;
>          goto fail;
>      }
>      offset -= 0x1d8;
>
> -    info_begin = read_off(bs, offset);
> -    if (info_begin == 0) {
> -       goto fail;
> +    ret = read_uint64(bs, offset, &info_begin);
> +    if (ret < 0) {
> +        goto fail;
> +    } else if (info_begin == 0) {
> +        ret = -EINVAL;
> +        goto fail;
>      }
>
> -    if (read_uint32(bs, info_begin) != 0x100) {
> +    ret = read_uint32(bs, info_begin, &tmp);
> +    if (ret < 0) {
> +        goto fail;
> +    } else if (tmp != 0x100) {
> +        ret = -EINVAL;
>          goto fail;
>      }
>
> -    count = read_uint32(bs, info_begin + 4);
> -    if (count == 0) {
> +    ret = read_uint32(bs, info_begin + 4, &count);
> +    if (ret < 0) {
> +        goto fail;
> +    } else if (count == 0) {
> +        ret = -EINVAL;
>          goto fail;
>      }
>      info_end = info_begin + count;
> @@ -114,12 +138,20 @@ static int dmg_open(BlockDriverState *bs, int flags)
>      while (offset < info_end) {
>          uint32_t type;
>
> -       count = read_uint32(bs, offset);
> -       if(count==0)
> -           goto fail;
> +        ret = read_uint32(bs, offset, &count);
> +        if (ret < 0) {
> +            goto fail;
> +        } else if (count == 0) {
> +            ret = -EINVAL;
> +            goto fail;
> +        }
>          offset += 4;
>
> -       type = read_uint32(bs, offset);
> +        ret = read_uint32(bs, offset, &type);
> +        if (ret < 0) {
> +            goto fail;
> +        }
> +
>         if (type == 0x6d697368 && count >= 244) {
>             int new_size, chunk_count;
>
> @@ -134,8 +166,11 @@ static int dmg_open(BlockDriverState *bs, int flags)
>             s->sectors = g_realloc(s->sectors, new_size);
>             s->sectorcounts = g_realloc(s->sectorcounts, new_size);
>
> -           for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
> -               s->types[i] = read_uint32(bs, offset);
> +            for (i = s->n_chunks; i < s->n_chunks + chunk_count; i++) {
> +                ret = read_uint32(bs, offset, &s->types[i]);
> +                if (ret < 0) {
> +                    goto fail;
> +                }
>                 offset += 4;
>                 if(s->types[i]!=0x80000005 && s->types[i]!=1 && 
> s->types[i]!=2) {
>                     if(s->types[i]==0xffffffff) {
> @@ -149,17 +184,31 @@ static int dmg_open(BlockDriverState *bs, int flags)
>                 }
>                 offset += 4;
>
> -               s->sectors[i] = last_out_offset+read_off(bs, offset);
> -               offset += 8;
> -
> -               s->sectorcounts[i] = read_off(bs, offset);
> -               offset += 8;
> -
> -               s->offsets[i] = last_in_offset+read_off(bs, offset);
> -               offset += 8;
> -
> -               s->lengths[i] = read_off(bs, offset);
> -               offset += 8;
> +                ret = read_uint64(bs, offset, &s->sectors[i]);
> +                if (ret < 0) {
> +                    goto fail;
> +                }
> +                s->sectors[i] += last_out_offset;
> +                offset += 8;
> +
> +                ret = read_uint64(bs, offset, &s->sectorcounts[i]);
> +                if (ret < 0) {
> +                    goto fail;
> +                }
> +                offset += 8;
> +
> +                ret = read_uint64(bs, offset, &s->offsets[i]);
> +                if (ret < 0) {
> +                    goto fail;
> +                }
> +                s->offsets[i] += last_in_offset;
> +                offset += 8;
> +
> +                ret = read_uint64(bs, offset, &s->lengths[i]);
> +                if (ret < 0) {
> +                    goto fail;
> +                }
> +                offset += 8;
>
>                 if(s->lengths[i]>max_compressed_size)
>                     max_compressed_size = s->lengths[i];
> @@ -173,15 +222,25 @@ static int dmg_open(BlockDriverState *bs, int flags)
>      /* initialize zlib engine */
>      s->compressed_chunk = g_malloc(max_compressed_size+1);
>      s->uncompressed_chunk = g_malloc(512*max_sectors_per_chunk);
> -    if(inflateInit(&s->zstream) != Z_OK)
> -       goto fail;
> +    if(inflateInit(&s->zstream) != Z_OK) {

Please add a space between 'if' and '('.

> +        ret = -EINVAL;
> +        goto fail;
> +    }
>
>      s->current_chunk = s->n_chunks;
>
>      qemu_co_mutex_init(&s->lock);
>      return 0;
> +
>  fail:
> -    return -1;
> +    g_free(s->types);
> +    g_free(s->offsets);
> +    g_free(s->lengths);
> +    g_free(s->sectors);
> +    g_free(s->sectorcounts);
> +    g_free(s->compressed_chunk);
> +    g_free(s->uncompressed_chunk);
> +    return ret;
>  }
>
>  static inline int is_sector_in_chunk(BDRVDMGState* s,
> --
> 1.8.1
>
>