Patchwork qemu-ga: ga_get_fd_handle(): abort if fd_counter overflows

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Submitter Luiz Capitulino
Date March 22, 2013, 8:31 p.m.
Message ID <20130322163107.489dd941@doriath>
Download mbox | patch
Permalink /patch/230251/
State New
Headers show

Comments

Luiz Capitulino - March 22, 2013, 8:31 p.m.
Today we reset fd_counter if it wraps, but it's better to abort()
instead, as fd_counter should never reach INT64_MAX.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 qga/main.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
Eric Blake - March 22, 2013, 8:44 p.m.
On 03/22/2013 02:31 PM, Luiz Capitulino wrote:
> Today we reset fd_counter if it wraps, but it's better to abort()
> instead, as fd_counter should never reach INT64_MAX.
> 
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> ---
>  qga/main.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 


> diff --git a/qga/main.c b/qga/main.c
> index 74ef788..5f505a2 100644
> --- a/qga/main.c
> +++ b/qga/main.c
> @@ -889,9 +889,13 @@ int64_t ga_get_fd_handle(GAState *s, Error **errp)
>      g_assert(!ga_is_frozen(s));
>  
>      handle = s->pstate.fd_counter++;
> -    if (s->pstate.fd_counter < 0) {
> -        s->pstate.fd_counter = 0;
> +
> +    /* This should never happen on a resonable timeframe, as guest-file-open

s/resonable/reasonable/

> +     * would have to be issued 2^63 times */
> +    if (s->pstate.fd_counter == INT64_MAX) {
> +        abort();

Fix the typo, and you can add:

Reviewed-by: Eric Blake <eblake@redhat.com>
Luiz Capitulino - March 22, 2013, 8:47 p.m.
On Fri, 22 Mar 2013 14:44:05 -0600
Eric Blake <eblake@redhat.com> wrote:

> On 03/22/2013 02:31 PM, Luiz Capitulino wrote:
> > Today we reset fd_counter if it wraps, but it's better to abort()
> > instead, as fd_counter should never reach INT64_MAX.
> > 
> > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> > ---
> >  qga/main.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> 
> 
> > diff --git a/qga/main.c b/qga/main.c
> > index 74ef788..5f505a2 100644
> > --- a/qga/main.c
> > +++ b/qga/main.c
> > @@ -889,9 +889,13 @@ int64_t ga_get_fd_handle(GAState *s, Error **errp)
> >      g_assert(!ga_is_frozen(s));
> >  
> >      handle = s->pstate.fd_counter++;
> > -    if (s->pstate.fd_counter < 0) {
> > -        s->pstate.fd_counter = 0;
> > +
> > +    /* This should never happen on a resonable timeframe, as guest-file-open
> 
> s/resonable/reasonable/

Michael, can you fix it for me?

> 
> > +     * would have to be issued 2^63 times */
> > +    if (s->pstate.fd_counter == INT64_MAX) {
> > +        abort();
> 
> Fix the typo, and you can add:
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>

Thanks!
Michael Roth - March 25, 2013, 4:20 p.m.
On Fri, Mar 22, 2013 at 04:31:07PM -0400, Luiz Capitulino wrote:
> Today we reset fd_counter if it wraps, but it's better to abort()
> instead, as fd_counter should never reach INT64_MAX.
> 
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

Thanks, applied to qga branch with s/resonable/reasonable/ typo fix.

> ---
>  qga/main.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/qga/main.c b/qga/main.c
> index 74ef788..5f505a2 100644
> --- a/qga/main.c
> +++ b/qga/main.c
> @@ -889,9 +889,13 @@ int64_t ga_get_fd_handle(GAState *s, Error **errp)
>      g_assert(!ga_is_frozen(s));
> 
>      handle = s->pstate.fd_counter++;
> -    if (s->pstate.fd_counter < 0) {
> -        s->pstate.fd_counter = 0;
> +
> +    /* This should never happen on a resonable timeframe, as guest-file-open
> +     * would have to be issued 2^63 times */
> +    if (s->pstate.fd_counter == INT64_MAX) {
> +        abort();
>      }
> +
>      if (!write_persistent_state(&s->pstate, s->pstate_filepath)) {
>          error_setg(errp, "failed to commit persistent state to disk");
>      }
> -- 
> 1.8.1.4
>

Patch

diff --git a/qga/main.c b/qga/main.c
index 74ef788..5f505a2 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -889,9 +889,13 @@  int64_t ga_get_fd_handle(GAState *s, Error **errp)
     g_assert(!ga_is_frozen(s));
 
     handle = s->pstate.fd_counter++;
-    if (s->pstate.fd_counter < 0) {
-        s->pstate.fd_counter = 0;
+
+    /* This should never happen on a resonable timeframe, as guest-file-open
+     * would have to be issued 2^63 times */
+    if (s->pstate.fd_counter == INT64_MAX) {
+        abort();
     }
+
     if (!write_persistent_state(&s->pstate, s->pstate_filepath)) {
         error_setg(errp, "failed to commit persistent state to disk");
     }