* [Qemu-devel] [PATCH] monitor: fix use after free
@ 2014-08-17 9:45 Michael S. Tsirkin
2014-08-18 18:05 ` Luiz Capitulino
0 siblings, 1 reply; 4+ messages in thread
From: Michael S. Tsirkin @ 2014-08-17 9:45 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, Igor Mammedov, zhanghailiang, Luiz Capitulino
The function monitor_fdset_dup_fd_find_remove() references member of
'mon_fdset' which - when remove flag is set - may be freed in function
monitor_fdset_cleanup().
remove is set by monitor_fdset_dup_fd_remove which in practice
does not need the returned value, so make it void,
and return -1 from monitor_fdset_dup_fd_find_remove.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
---
include/monitor/monitor.h | 2 +-
monitor.c | 8 +++++---
stubs/fdset-remove-fd.c | 3 +--
3 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
index 3d6929d..78a5fc8 100644
--- a/include/monitor/monitor.h
+++ b/include/monitor/monitor.h
@@ -64,7 +64,7 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
Error **errp);
int monitor_fdset_get_fd(int64_t fdset_id, int flags);
int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);
-int monitor_fdset_dup_fd_remove(int dup_fd);
+void monitor_fdset_dup_fd_remove(int dup_fd);
int monitor_fdset_dup_fd_find(int dup_fd);
#endif /* !MONITOR_H */
diff --git a/monitor.c b/monitor.c
index cdbaa60..ba1908f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2542,8 +2542,10 @@ static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
monitor_fdset_cleanup(mon_fdset);
}
+ return -1;
+ } else {
+ return mon_fdset->id;
}
- return mon_fdset->id;
}
}
}
@@ -2555,9 +2557,9 @@ int monitor_fdset_dup_fd_find(int dup_fd)
return monitor_fdset_dup_fd_find_remove(dup_fd, false);
}
-int monitor_fdset_dup_fd_remove(int dup_fd)
+void monitor_fdset_dup_fd_remove(int dup_fd)
{
- return monitor_fdset_dup_fd_find_remove(dup_fd, true);
+ monitor_fdset_dup_fd_find_remove(dup_fd, true);
}
int monitor_handle_fd_param(Monitor *mon, const char *fdname)
diff --git a/stubs/fdset-remove-fd.c b/stubs/fdset-remove-fd.c
index b3886d9..7f6d61e 100644
--- a/stubs/fdset-remove-fd.c
+++ b/stubs/fdset-remove-fd.c
@@ -1,7 +1,6 @@
#include "qemu-common.h"
#include "monitor/monitor.h"
-int monitor_fdset_dup_fd_remove(int dupfd)
+void monitor_fdset_dup_fd_remove(int dupfd)
{
- return -1;
}
--
MST
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] monitor: fix use after free
2014-08-17 9:45 [Qemu-devel] [PATCH] monitor: fix use after free Michael S. Tsirkin
@ 2014-08-18 18:05 ` Luiz Capitulino
2014-08-18 20:03 ` Michael S. Tsirkin
0 siblings, 1 reply; 4+ messages in thread
From: Luiz Capitulino @ 2014-08-18 18:05 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: Kevin Wolf, Igor Mammedov, qemu-devel, zhanghailiang
On Sun, 17 Aug 2014 11:45:17 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> The function monitor_fdset_dup_fd_find_remove() references member of
> 'mon_fdset' which - when remove flag is set - may be freed in function
> monitor_fdset_cleanup().
> remove is set by monitor_fdset_dup_fd_remove which in practice
> does not need the returned value, so make it void,
> and return -1 from monitor_fdset_dup_fd_find_remove.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Reported-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
I've applied this one to the qmp tree, but I have one comment below.
> ---
> include/monitor/monitor.h | 2 +-
> monitor.c | 8 +++++---
> stubs/fdset-remove-fd.c | 3 +--
> 3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> index 3d6929d..78a5fc8 100644
> --- a/include/monitor/monitor.h
> +++ b/include/monitor/monitor.h
> @@ -64,7 +64,7 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
> Error **errp);
> int monitor_fdset_get_fd(int64_t fdset_id, int flags);
> int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);
> -int monitor_fdset_dup_fd_remove(int dup_fd);
> +void monitor_fdset_dup_fd_remove(int dup_fd);
> int monitor_fdset_dup_fd_find(int dup_fd);
>
> #endif /* !MONITOR_H */
> diff --git a/monitor.c b/monitor.c
> index cdbaa60..ba1908f 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -2542,8 +2542,10 @@ static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
> monitor_fdset_cleanup(mon_fdset);
> }
> + return -1;
Returning -1 here looks wrong. A better fix is probably to split this
function into two functions as it's doing two unrelated things currently.
I've applied the fix anyway because the only user of remove=true doesn't
care about the return value and also because the bad semantic is less worse
than the use after free...
> + } else {
> + return mon_fdset->id;
> }
> - return mon_fdset->id;
> }
> }
> }
> @@ -2555,9 +2557,9 @@ int monitor_fdset_dup_fd_find(int dup_fd)
> return monitor_fdset_dup_fd_find_remove(dup_fd, false);
> }
>
> -int monitor_fdset_dup_fd_remove(int dup_fd)
> +void monitor_fdset_dup_fd_remove(int dup_fd)
> {
> - return monitor_fdset_dup_fd_find_remove(dup_fd, true);
> + monitor_fdset_dup_fd_find_remove(dup_fd, true);
> }
>
> int monitor_handle_fd_param(Monitor *mon, const char *fdname)
> diff --git a/stubs/fdset-remove-fd.c b/stubs/fdset-remove-fd.c
> index b3886d9..7f6d61e 100644
> --- a/stubs/fdset-remove-fd.c
> +++ b/stubs/fdset-remove-fd.c
> @@ -1,7 +1,6 @@
> #include "qemu-common.h"
> #include "monitor/monitor.h"
>
> -int monitor_fdset_dup_fd_remove(int dupfd)
> +void monitor_fdset_dup_fd_remove(int dupfd)
> {
> - return -1;
> }
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] monitor: fix use after free
2014-08-18 18:05 ` Luiz Capitulino
@ 2014-08-18 20:03 ` Michael S. Tsirkin
2014-08-19 12:55 ` Luiz Capitulino
0 siblings, 1 reply; 4+ messages in thread
From: Michael S. Tsirkin @ 2014-08-18 20:03 UTC (permalink / raw)
To: Luiz Capitulino; +Cc: Kevin Wolf, Igor Mammedov, qemu-devel, zhanghailiang
On Mon, Aug 18, 2014 at 02:05:46PM -0400, Luiz Capitulino wrote:
> On Sun, 17 Aug 2014 11:45:17 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > The function monitor_fdset_dup_fd_find_remove() references member of
> > 'mon_fdset' which - when remove flag is set - may be freed in function
> > monitor_fdset_cleanup().
> > remove is set by monitor_fdset_dup_fd_remove which in practice
> > does not need the returned value, so make it void,
> > and return -1 from monitor_fdset_dup_fd_find_remove.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > Reported-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>
> I've applied this one to the qmp tree, but I have one comment below.
>
> > ---
> > include/monitor/monitor.h | 2 +-
> > monitor.c | 8 +++++---
> > stubs/fdset-remove-fd.c | 3 +--
> > 3 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> > index 3d6929d..78a5fc8 100644
> > --- a/include/monitor/monitor.h
> > +++ b/include/monitor/monitor.h
> > @@ -64,7 +64,7 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
> > Error **errp);
> > int monitor_fdset_get_fd(int64_t fdset_id, int flags);
> > int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);
> > -int monitor_fdset_dup_fd_remove(int dup_fd);
> > +void monitor_fdset_dup_fd_remove(int dup_fd);
> > int monitor_fdset_dup_fd_find(int dup_fd);
> >
> > #endif /* !MONITOR_H */
> > diff --git a/monitor.c b/monitor.c
> > index cdbaa60..ba1908f 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -2542,8 +2542,10 @@ static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> > if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
> > monitor_fdset_cleanup(mon_fdset);
> > }
> > + return -1;
>
> Returning -1 here looks wrong. A better fix is probably to split this
> function into two functions as it's doing two unrelated things currently.
>
> I've applied the fix anyway because the only user of remove=true doesn't
> care about the return value and also because the bad semantic is less worse
> than the use after free...
I agree generally, it's just that I don't understand this function.
For example, doesn't it leak memory? When
monitor_fdset_dup_fd_find_remove drops a MonFdsetFd entry from list, it does
not seem to free it.
> > + } else {
> > + return mon_fdset->id;
> > }
> > - return mon_fdset->id;
> > }
> > }
> > }
> > @@ -2555,9 +2557,9 @@ int monitor_fdset_dup_fd_find(int dup_fd)
> > return monitor_fdset_dup_fd_find_remove(dup_fd, false);
> > }
> >
> > -int monitor_fdset_dup_fd_remove(int dup_fd)
> > +void monitor_fdset_dup_fd_remove(int dup_fd)
> > {
> > - return monitor_fdset_dup_fd_find_remove(dup_fd, true);
> > + monitor_fdset_dup_fd_find_remove(dup_fd, true);
> > }
> >
> > int monitor_handle_fd_param(Monitor *mon, const char *fdname)
> > diff --git a/stubs/fdset-remove-fd.c b/stubs/fdset-remove-fd.c
> > index b3886d9..7f6d61e 100644
> > --- a/stubs/fdset-remove-fd.c
> > +++ b/stubs/fdset-remove-fd.c
> > @@ -1,7 +1,6 @@
> > #include "qemu-common.h"
> > #include "monitor/monitor.h"
> >
> > -int monitor_fdset_dup_fd_remove(int dupfd)
> > +void monitor_fdset_dup_fd_remove(int dupfd)
> > {
> > - return -1;
> > }
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] monitor: fix use after free
2014-08-18 20:03 ` Michael S. Tsirkin
@ 2014-08-19 12:55 ` Luiz Capitulino
0 siblings, 0 replies; 4+ messages in thread
From: Luiz Capitulino @ 2014-08-19 12:55 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: Kevin Wolf, famz, zhanghailiang, coreyb, qemu-devel,
Igor Mammedov
On Mon, 18 Aug 2014 22:03:31 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Mon, Aug 18, 2014 at 02:05:46PM -0400, Luiz Capitulino wrote:
> > On Sun, 17 Aug 2014 11:45:17 +0200
> > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> >
> > > The function monitor_fdset_dup_fd_find_remove() references member of
> > > 'mon_fdset' which - when remove flag is set - may be freed in function
> > > monitor_fdset_cleanup().
> > > remove is set by monitor_fdset_dup_fd_remove which in practice
> > > does not need the returned value, so make it void,
> > > and return -1 from monitor_fdset_dup_fd_find_remove.
> > >
> > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > Reported-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> >
> > I've applied this one to the qmp tree, but I have one comment below.
> >
> > > ---
> > > include/monitor/monitor.h | 2 +-
> > > monitor.c | 8 +++++---
> > > stubs/fdset-remove-fd.c | 3 +--
> > > 3 files changed, 7 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> > > index 3d6929d..78a5fc8 100644
> > > --- a/include/monitor/monitor.h
> > > +++ b/include/monitor/monitor.h
> > > @@ -64,7 +64,7 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
> > > Error **errp);
> > > int monitor_fdset_get_fd(int64_t fdset_id, int flags);
> > > int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);
> > > -int monitor_fdset_dup_fd_remove(int dup_fd);
> > > +void monitor_fdset_dup_fd_remove(int dup_fd);
> > > int monitor_fdset_dup_fd_find(int dup_fd);
> > >
> > > #endif /* !MONITOR_H */
> > > diff --git a/monitor.c b/monitor.c
> > > index cdbaa60..ba1908f 100644
> > > --- a/monitor.c
> > > +++ b/monitor.c
> > > @@ -2542,8 +2542,10 @@ static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> > > if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
> > > monitor_fdset_cleanup(mon_fdset);
> > > }
> > > + return -1;
> >
> > Returning -1 here looks wrong. A better fix is probably to split this
> > function into two functions as it's doing two unrelated things currently.
> >
> > I've applied the fix anyway because the only user of remove=true doesn't
> > care about the return value and also because the bad semantic is less worse
> > than the use after free...
>
>
> I agree generally, it's just that I don't understand this function.
> For example, doesn't it leak memory? When
> monitor_fdset_dup_fd_find_remove drops a MonFdsetFd entry from list, it does
> not seem to free it.
It seems so. Corey, are you still around? Can you take a look at this?
>
>
>
> > > + } else {
> > > + return mon_fdset->id;
> > > }
> > > - return mon_fdset->id;
> > > }
> > > }
> > > }
> > > @@ -2555,9 +2557,9 @@ int monitor_fdset_dup_fd_find(int dup_fd)
> > > return monitor_fdset_dup_fd_find_remove(dup_fd, false);
> > > }
> > >
> > > -int monitor_fdset_dup_fd_remove(int dup_fd)
> > > +void monitor_fdset_dup_fd_remove(int dup_fd)
> > > {
> > > - return monitor_fdset_dup_fd_find_remove(dup_fd, true);
> > > + monitor_fdset_dup_fd_find_remove(dup_fd, true);
> > > }
> > >
> > > int monitor_handle_fd_param(Monitor *mon, const char *fdname)
> > > diff --git a/stubs/fdset-remove-fd.c b/stubs/fdset-remove-fd.c
> > > index b3886d9..7f6d61e 100644
> > > --- a/stubs/fdset-remove-fd.c
> > > +++ b/stubs/fdset-remove-fd.c
> > > @@ -1,7 +1,6 @@
> > > #include "qemu-common.h"
> > > #include "monitor/monitor.h"
> > >
> > > -int monitor_fdset_dup_fd_remove(int dupfd)
> > > +void monitor_fdset_dup_fd_remove(int dupfd)
> > > {
> > > - return -1;
> > > }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-08-19 12:56 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2014-08-17 9:45 [Qemu-devel] [PATCH] monitor: fix use after free Michael S. Tsirkin
2014-08-18 18:05 ` Luiz Capitulino
2014-08-18 20:03 ` Michael S. Tsirkin
2014-08-19 12:55 ` Luiz Capitulino
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