From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37630) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XIMCo-0000GF-4E for qemu-devel@nongnu.org; Fri, 15 Aug 2014 14:26:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XIMCj-0001lG-5V for qemu-devel@nongnu.org; Fri, 15 Aug 2014 14:26:26 -0400 Date: Fri, 15 Aug 2014 14:25:51 -0400 From: Luiz Capitulino Message-ID: <20140815142551.5230d23a@redhat.com> In-Reply-To: <20140814103010.GE31346@redhat.com> References: <1408001361-13580-1-git-send-email-zhang.zhanghailiang@huawei.com> <1408001361-13580-3-git-send-email-zhang.zhanghailiang@huawei.com> <20140814103010.GE31346@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v6 02/10] monitor: fix access freed memory List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: kwolf@redhat.com, lkurusa@redhat.com, zhanghailiang , qemu-trivial@nongnu.org, jan.kiszka@siemens.com, riku.voipio@iki.fi, mjt@tls.msk.ru, qemu-devel@nongnu.org, peter.huangpeng@huawei.com, stefanha@redhat.com, luonengjun@huawei.com, pbonzini@redhat.com, alex.bennee@linaro.org, rth@twiddle.net On Thu, 14 Aug 2014 12:30:10 +0200 "Michael S. Tsirkin" wrote: > On Thu, Aug 14, 2014 at 03:29:13PM +0800, zhanghailiang wrote: > > The function monitor_fdset_dup_fd_find_remove() references member of 'mon_fdset' > > which may be freed in function monitor_fdset_cleanup() > > > > Reviewed-by: Gonglei > > Signed-off-by: zhanghailiang > > Id doesn't make sense after fdset is gone. > A cleaner way would be return -1 within that remove > clause. > > ---> > > monitor: fix use after free > > 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 Looks correct to me, can you post as a toplevel patch please? > > --- > > 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 5bc70a6..ef28328 100644 > --- a/monitor.c > +++ b/monitor.c > @@ -2541,8 +2541,10 @@ 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; > } > } > } > @@ -2554,9 +2556,9 @@ 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; > } >