Date: Fri, 11 Sep 2015 04:44:06 +0900 From: sfjro@...rs.sourceforge.net To: Ben Hutchings <ben@...adent.org.uk> Cc: oss-security <oss-security@...ts.openwall.com> Subject: Re: CVE request: Use-after-free in Linux kernel with aufs mmap patch Ben Hutchings: > The aufs (Advanced Union Filesystem) project provides an optional patch > for the Linux kernel, called either aufs3-mmap.patch or ::: > I posted a patch here that works for me: > http://sourceforge.net/p/aufs/mailman/message/34449209/ > > Please assign a CVE ID to this. I know this is a bug but I don't have time to fix it or test your patch. I am afraid your patch may introduce another problem because you don't handle vm_prfile. I still think get/put(vm_prfile) is necessary. Its lifetime should be equivalent to vm_file's essentially. How about the test case for the race condition between these? - groupA: msync or madvise - groupB: mmap and munmap As you might know, aufs mmap/munmap handle vm_file and vm_prfile. When aufs munmap calls fput(vm_prfile) and your patch doesn't fget(vm_prfile), then vm_prfile will be broken. And I am afraid it will cause a problem like use-after-free. I have no objection to assign a CVE ID, but I don't think it is fixed or at least I didn't confirmt yet. J. R. Okajima
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