Date: Thu, 04 Feb 2010 13:09:09 +0800 From: Eugene Teo <eugene@...hat.com> To: oss-security@...ts.openwall.com CC: dann frazier <dannf@...ian.org>, "Steven M. Christey" <coley@...us.mitre.org> Subject: Re: CVE request - kernel: DoS on x86_64 On 02/04/2010 10:28 AM, dann frazier wrote: > On Mon, Feb 01, 2010 at 01:09:12PM +0800, Eugene Teo wrote: >> Reported by Mathias Krause. The problem seams to be located in >> fs/binfmt_elf.c:load_elf_binary(). It calls SET_PERSONALITY() prior >> checking that the ELF interpreter is available. This in turn makes the >> previously 32 bit process a 64 bit one which would be fine if execve() >> would succeed. But after the SET_PERSONALITY() the open_exec() call >> fails (because it cannot find the interpreter) and execve() almost >> instantly returns with an error. If you now look at /proc/PID/maps >> you'll see, that it has the vsyscall page mapped which shouldn't be. But >> the process is not dead yet, it's still running. By now generating a >> segmentation fault and in turn trying to generate a core dump the >> kernel just dies. >> >> Steps to Reproduce: >> 1. Enable core dumps >> 2. Start an 32 bit program that tries to execve() an 64 bit program >> 3. The 64 bit program cannot be started by the kernel because it can't >> find the interpreter, i.e. execve returns with an error >> 4. Generate a segmentation fault >> 5. panic >> >> Upstream commit: >> http://git.kernel.org/linus/221af7f87b97431e3ee21ce4b0e77d5411cf1549 > > Thanks Eugene. > > Also note this fix for a regression in the above: > http://git.kernel.org/linus/7ab02af428c2d312c0cf8fb0b01cc1eb21131a3d Ben Hutchings reported (via stable review list) that the fix did not work for him. Will monitor the list if there are other follow-ups. Thanks, Eugene -- Eugene Teo / Red Hat Security Response Team
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