Re: [Qemu-devel] [PATCH 7/8] migration: fix unbounded stack for source_return_path_thread

[Paolo Bonzini]

On 08/03/2016 08:00, Peter Xu wrote:
> Suggested-by: Paolo Bonzini <address@hidden>
> CC: Juan Quintela <address@hidden>
> CC: Amit Shah <address@hidden>
> Signed-off-by: Peter Xu <address@hidden>
> ---
>  migration/migration.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 0129d9f..f1a3976 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1265,11 +1265,11 @@ static void 
> migrate_handle_rp_req_pages(MigrationState *ms, const char* rbname,
>   */
>  static void *source_return_path_thread(void *opaque)
>  {
> +#define __MAX_LEN (512)
>      MigrationState *ms = opaque;
>      QEMUFile *rp = ms->rp_state.from_dst_file;
>      uint16_t header_len, header_type;
> -    const int max_len = 512;
> -    uint8_t buf[max_len];
> +    uint8_t buf[__MAX_LEN];
>      uint32_t tmp32, sibling_error;
>      ram_addr_t start = 0; /* =0 to silence warning */
>      size_t  len = 0, expected_len;
> @@ -1292,7 +1292,7 @@ static void *source_return_path_thread(void *opaque)
>  
>          if ((rp_cmd_args[header_type].len != -1 &&
>              header_len != rp_cmd_args[header_type].len) ||
> -            header_len > max_len) {
> +            header_len > __MAX_LEN) {
>              error_report("RP: Received '%s' message (0x%04x) with"
>                      "incorrect length %d expecting %zu",
>                      rp_cmd_args[header_type].name, header_type, header_len,
> @@ -1372,6 +1372,7 @@ out:
>      ms->rp_state.from_dst_file = NULL;
>      qemu_fclose(rp);
>      return NULL;
> +#undef __MAX_LEN
>  }
>  
>  static int open_return_path_on_source(MigrationState *ms)
> 

Another compiler false positive that you can fix with ARRAY_SIZE.

Paolo