Re: [PATCH 1/1] 9p-local.c: always return -1 on error in local_unlinkat_common

[Greg Kurz]

I've changed "9p-local.c:" to "9p: local:" which is the usual prefix used for
fsdev backend specific changes.

On Tue,  7 Jan 2020 11:47:18 -0300
Daniel Henrique Barboza <address@hidden> wrote:

> local_unlinkat_common() is supposed to always return -1 on error.
> This is being done by jumps to the 'err_out' label, which is
> a 'return ret' call, and 'ret' is initialized with -1.
> 
> Unfortunately there is a condition in which the function will
> return 0 on error: in a case where flags == AT_REMOVEDIR, 'ret'
> will be 0 when reaching
> 
> map_dirfd = openat_dir(...)
> 
> And, if map_dirfd == -1 and errno != ENOENT, the existing 'err_out'
> jump will execute 'return ret', when ret is still set to zero
> at that point.
> 
> This patch fixes it by changing all 'err_out' labels by
> 'return -1' calls, ensuring that the function will always
> return -1 on error conditions. 'ret' can be left unintialized
> since it's now being used just to store the result of 'unlinkat'
> calls.
> 
> CC: Greg Kurz <address@hidden>
> Signed-off-by: Daniel Henrique Barboza <address@hidden>
> ---

Applied to 9p-next.

Thanks Daniel and feliz ano novo :)

>  hw/9pfs/9p-local.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index ca641390fb..de61aca216 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -1076,7 +1076,7 @@ out:
>  static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name,
>                                   int flags)
>  {
> -    int ret = -1;
> +    int ret;
>  
>      if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
>          int map_dirfd;
> @@ -1094,12 +1094,12 @@ static int local_unlinkat_common(FsContext *ctx, int 
> dirfd, const char *name,
>  
>              fd = openat_dir(dirfd, name);
>              if (fd == -1) {
> -                goto err_out;
> +                return -1;
>              }
>              ret = unlinkat(fd, VIRTFS_META_DIR, AT_REMOVEDIR);
>              close_preserve_errno(fd);
>              if (ret < 0 && errno != ENOENT) {
> -                goto err_out;
> +                return -1;
>              }
>          }
>          map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
> @@ -1107,16 +1107,14 @@ static int local_unlinkat_common(FsContext *ctx, int 
> dirfd, const char *name,
>              ret = unlinkat(map_dirfd, name, 0);
>              close_preserve_errno(map_dirfd);
>              if (ret < 0 && errno != ENOENT) {
> -                goto err_out;
> +                return -1;
>              }
>          } else if (errno != ENOENT) {
> -            goto err_out;
> +            return -1;
>          }
>      }
>  
> -    ret = unlinkat(dirfd, name, flags);
> -err_out:
> -    return ret;
> +    return unlinkat(dirfd, name, flags);
>  }
>  
>  static int local_remove(FsContext *ctx, const char *path)