Date: Thu, 4 Feb 2010 15:46:02 -0700 From: dann frazier <dannf@...nf.org> To: oss-security@...ts.openwall.com Cc: "Steven M. Christey" <coley@...us.mitre.org> Subject: Re: CVE request - kernel: DoS on x86_64 On Thu, Feb 04, 2010 at 01:09:09PM +0800, Eugene Teo wrote: > 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. Indeed, it also needs this change for x86: http://git.kernel.org/linus/05d43ed8a89c159ff641d472f970e3f1baa66318 And the corresponding changes for powerpc & sparc: http://git.kernel.org/linus/94f28da8409c6059135e89ac64a0839993124155 http://git.kernel.org/linus/94673e968cbcce07fa78dac4b0ae05d24b5816e1 All are in queue-2.6.32 now, btw. -- dann frazier
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