Thanks！ It seems that the function do_page_fault() will finally call fast_clear_page()<http://lxr.oss.org.cn/plain/source/arch/x86/lib/mmx_32.c#L125> or slow_zero_page()<http://lxr.oss.org.cn/plain/source/arch/x86/lib/mmx_32.c#L336> to zero a new physical page for a process. So calling malloc() cannot get a page used by another process which is dead already.
The assemble language is difficult to me, so please tell me if I am wrong. 2012/1/18 Fredrick <[email protected]> > When you malloc a memory or mmap a MAP_ANON memory, it is virtually > allocated. When you read or write to it, the process takes a page fault. > The page fault handler zeroes those memory and hands it to the process. So > I think there is no leak. > > -Fredrick > > > On 01/11/2012 04:53 AM, 夏业添 wrote: > >> Hi, >> My tutor asked me to test whether one process leaves information in >> memory after it is dead. I tried to search some article about such thing >> on the Internet but there seems to be no one discuss about it. And after >> that, I tried to write some program in the User Mode to test it, using >> fork() to create lots of processes and filling char 'a' into a 102400 >> bytes char array in each process. Then I used malloc() to get some >> memory to seek char 'a' in a new one process or many new processes, but >> failed. All memory I malloced was full of zero. >> As the man page of malloc said:"The memory is not initialized", I >> believe that the memory which was got by malloc() could be used by other >> process, and therefor information leakage exists. But how can I test it? >> Or where can I get related information? >> Thanks! >> >> >> ______________________________**_________________ >> Kernelnewbies mailing list >> Kernelnewbies@kernelnewbies.**org <[email protected]> >> http://lists.kernelnewbies.**org/mailman/listinfo/**kernelnewbies<http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies> >> > > >
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