On Thu, 31 May 2007 14:09:15 -0400 Ulrich Drepper <[EMAIL PROTECTED]> wrote:
> I've brought this topic up before but didn't provide a patch. Well, here > we go again, this time with a patch. I even throw in a test program. > > The problem is as follows: in multi-threaded code (or more correctly: all > code using clone() with CLONE_FILES) we have a race when exec'ing. > > thread #1 thread #2 > > fd=open() > > fork + exec > > fcntl(fd,F_SETFD,FD_CLOEXEC) > > In some applications this can happen frequently. Take a web browser. One > thread opens a file and another thread starts, say, an external PDF viewer. > The result can even be a security issue if that open file descriptor refers > to a sensitive file and the external program can somehow be tricked into > using that descriptor. > > Just adding O_CLOEXEC support to open() doesn't solve the whole set of > problems. There are other ways to create file descriptors (socket, > epoll_create, Unix domain socket transfer, etc). These can and should > be addressed separately though. open() is such an easy case that it makes > not much sense putting the fix off. > > ... > > diff --git a/include/asm-generic/fcntl.h b/include/asm-generic/fcntl.h > index c154b9d..b847741 100644 > --- a/include/asm-generic/fcntl.h > +++ b/include/asm-generic/fcntl.h > @@ -48,6 +48,9 @@ > #ifndef O_NOATIME > #define O_NOATIME 01000000 > #endif > +#ifndef O_CLOEXEC > +#define O_CLOEXEC 02000000 /* set close_on_exec */ > +#endif > #ifndef O_NDELAY > #define O_NDELAY O_NONBLOCK > #endif This will break xtensa, because that architecture (and only that architecture) doesn't include asm-generic/fcntl.h from asm/fcntl.h. But let's leave this patch as-is: it's xtensa which needs fixing. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
