Re: [Qemu-devel] [PATCH 07/31] 9pfs: Fix CLI parsing crash on error

[Greg Kurz]

On Mon,  8 Oct 2018 19:31:01 +0200
Markus Armbruster <address@hidden> wrote:

> Calling error_report() in a function that takes an Error ** argument
> is suspicious.  9p-handle.c's handle_parse_opts() does that, and then
> fails without setting an error.  Wrong.  Its caller crashes when it
> tries to report the error:
> 
>     $ qemu-system-x86_64 -nodefaults -fsdev id=foo,fsdriver=handle
>     qemu-system-x86_64: -fsdev id=foo,fsdriver=handle: warning: handle 
> backend is deprecated
>     qemu-system-x86_64: -fsdev id=foo,fsdriver=handle: fsdev: No path 
> specified
>     Segmentation fault (core dumped)
> 
> Screwed up when commit 91cda4e8f37 (v2.12.0) converted the function to
> Error.  Fix by calling error_setg() instead of error_report().
> 

The 9p-handle backend has entered the deprecation process in 2.12... I
strongly suspect parapraxis here :) but, you're right, bugs need to be
fixed until the code gets removed in 3.2.

Acked-by: Greg Kurz <address@hidden>

> Fixes: 91cda4e8f372602795e3a2f4bd2e3adaf9f82255
> Cc: Greg Kurz <address@hidden>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>  hw/9pfs/9p-handle.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/9pfs/9p-handle.c b/hw/9pfs/9p-handle.c
> index f3641dbe4a..3465b1ef30 100644
> --- a/hw/9pfs/9p-handle.c
> +++ b/hw/9pfs/9p-handle.c
> @@ -19,6 +19,7 @@
>  #include <grp.h>
>  #include <sys/socket.h>
>  #include <sys/un.h>
> +#include "qapi/error.h"
>  #include "qemu/xattr.h"
>  #include "qemu/cutils.h"
>  #include "qemu/error-report.h"
> @@ -655,12 +656,13 @@ static int handle_parse_opts(QemuOpts *opts, 
> FsDriverEntry *fse, Error **errp)
>      warn_report("handle backend is deprecated");
>  
>      if (sec_model) {
> -        error_report("Invalid argument security_model specified with handle 
> fsdriver");
> +        error_setg(errp,
> +                   "Invalid argument security_model specified with handle 
> fsdriver");
>          return -1;
>      }
>  
>      if (!path) {
> -        error_report("fsdev: No path specified");
> +        error_setg(errp, "fsdev: No path specified");
>          return -1;
>      }
>      fse->path = g_strdup(path);