On 10/11/2018 06:02 PM, Markus Armbruster wrote:
Fei Li <f...@suse.com> writes:
Currently, when qemu_signal_init() fails it only returns a non-zero
value but without propagating any Error. But its callers need a
non-null err when runs error_report_err(err), or else 0->msg occurs.
The bug is in qemu_init_main_loop():
ret = qemu_signal_init();
if (ret) {
return ret;
}
Fails without setting an error, unlike the other failures. Its callers
crash then.
Thanks!
To avoid such segmentation fault, add a new Error parameter to make
the call trace to propagate the err to the final caller.
Signed-off-by: Fei Li <f...@suse.com>
Reviewed-by: Fam Zheng <f...@redhat.com>
---
include/qemu/osdep.h | 2 +-
util/compatfd.c | 9 ++++++---
util/main-loop.c | 9 ++++-----
3 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 4f8559e550..f1f56763a0 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -421,7 +421,7 @@ struct qemu_signalfd_siginfo {
additional fields in the future) */
};
-int qemu_signalfd(const sigset_t *mask);
+int qemu_signalfd(const sigset_t *mask, Error **errp);
void sigaction_invoke(struct sigaction *action,
struct qemu_signalfd_siginfo *info);
#endif
diff --git a/util/compatfd.c b/util/compatfd.c
index 980bd33e52..d3ed890405 100644
--- a/util/compatfd.c
+++ b/util/compatfd.c
@@ -16,6 +16,7 @@
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/thread.h"
+#include "qapi/error.h"
#include <sys/syscall.h>
@@ -65,7 +66,7 @@ static void *sigwait_compat(void *opaque)
}
}
-static int qemu_signalfd_compat(const sigset_t *mask)
+static int qemu_signalfd_compat(const sigset_t *mask, Error **errp)
{
struct sigfd_compat_info *info;
QemuThread thread;
@@ -73,11 +74,13 @@ static int qemu_signalfd_compat(const sigset_t *mask)
info = malloc(sizeof(*info));
if (info == NULL) {
+ error_setg(errp, "Failed to allocate signalfd memory");
errno = ENOMEM;
return -1;
}
if (pipe(fds) == -1) {
+ error_setg(errp, "Failed to create signalfd pipe");
free(info);
return -1;
}
@@ -94,7 +97,7 @@ static int qemu_signalfd_compat(const sigset_t *mask)
return fds[0];
}
-int qemu_signalfd(const sigset_t *mask)
+int qemu_signalfd(const sigset_t *mask, Error **errp)
{
#if defined(CONFIG_SIGNALFD)
int ret;
@@ -106,5 +109,5 @@ int qemu_signalfd(const sigset_t *mask)
}
#endif
- return qemu_signalfd_compat(mask);
+ return qemu_signalfd_compat(mask, errp);
}
I think this takes the Error conversion too far.
qemu_signalfd() is like the signalfd() system call, only portable, and
setting FD_CLOEXEC. In particular, it reports failure just like a
system call: it sets errno and returns -1. I'd prefer to keep it that
way. Instead...
diff --git a/util/main-loop.c b/util/main-loop.c
index affe0403c5..9671b6d226 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -71,7 +71,7 @@ static void sigfd_handler(void *opaque)
}
}
-static int qemu_signal_init(void)
+static int qemu_signal_init(Error **errp)
{
int sigfd;
sigset_t set;
@@ -94,9 +94,8 @@ static int qemu_signal_init(void)
pthread_sigmask(SIG_BLOCK, &set, NULL);
sigdelset(&set, SIG_IPI);
- sigfd = qemu_signalfd(&set);
+ sigfd = qemu_signalfd(&set, errp);
if (sigfd == -1) {
- fprintf(stderr, "failed to create signalfd\n");
return -errno;
}
... change this function so:
pthread_sigmask(SIG_BLOCK, &set, NULL);
sigdelset(&set, SIG_IPI);
sigfd = qemu_signalfd(&set);
if (sigfd == -1) {
- fprintf(stderr, "failed to create signalfd\n");
+ error_setg_errno(errp, errno, "failed to create signalfd");
return -errno;
}
Does this make sense?
Yes, it looks more concise if we only have this patch, but triggers one
errno-set
issue after applying patch 7/7, which adds a Error **errp parameter for
qemu_thread_create() to let its callers handle the error instead of
exit() directly
to add the robustness.
For the patch series' current implementation, the modified
qemu_thread_create()
in 7/7 patch returns a Boolean value to indicate whether it succeeds and
set the
error reason into the passed errp, and did not set the errno. Actually
another
similar errno-set issue has been talked in last patch. :)
If we set the errno in future qemu_thread_create(), we need to
distinguish the Linux
and Windows implementation. For Linux, we can use error_setg_errno() to
set errno.
But for Windows, I am not sure if we can use
"errno = GetLastError()"
to set errno, as this seems a little weird. Do you have any idea about this?
BTW, if we have a decent errno-set way for Windows, I will adopt your above
proposal for this patch.
Have a nice day, thanks for the review :)
Fei
@@ -109,7 +108,7 @@ static int qemu_signal_init(void)
#else /* _WIN32 */
-static int qemu_signal_init(void)
+static int qemu_signal_init(Error **errp)
{
return 0;
}
@@ -148,7 +147,7 @@ int qemu_init_main_loop(Error **errp)
init_clocks(qemu_timer_notify_cb);
- ret = qemu_signal_init();
+ ret = qemu_signal_init(errp);
if (ret) {
return ret;
}
