On 2014/8/5 14:50, Levente Kurusa wrote:
----- Original Message -----
Hi Michael,
Thanks for your review of this patch!
On Mon, Aug 04, 2014 at 04:25:44PM +0800, zhanghailiang wrote:
The function fstat() may fail, so check its return value.
Signed-off-by: zhanghailiang<zhang.zhanghaili...@huawei.com>
---
hw/misc/ivshmem.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 768e528..2667e9f 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -324,7 +324,10 @@ static int check_shm_size(IVShmemState *s, int fd) {
struct stat buf;
- fstat(fd,&buf);
+ if (fstat(fd,&buf)< 0) {
+ fprintf(stderr, "Cannot stat IVSHMEM: %s\n", strerror(errno));
+ return -1;
+ }
That's a confusing error message:
1. You don't stat ivshmem. You stat a shmem fd. Also best to print fd #.
I will add this in next version of the patch.
2. Tell the user what action was taken, e.g. IVSHMEM failed to start.
if (s->ivshmem_size> buf.st_size) {
fprintf(stderr,
--
I have check the places of calling this function, And found that, if
this function return -1, qemu will call exit(-1). One of the callers is
ivshmem_read(), the purpose of check_shm_size() is to forbid guest to
map more memory than the object has allocated. So here is it suitable to
return -1 if fstat() failed? Or just give a warning message and return 0?
what's your opinion? Thanks.
Yes, please return -1. All the errors fstat(2) can return in this scenario
will be fatal to ivshmem.
Exiting is probably not the best way to go, but I'm working on a fix for
that at the moment, and for now, let's just exit, like all the other error
paths do.
Thanks,
Levente Kurusa
OK,thanks!
Best regards,
zhanghailiang
