Date: Tue, 22 Jun 2004 15:30:45 +0200 From: Marceta Milos <root@marcetam.net> To: des@des.no Cc: alpha@freebsd.org Subject: Re: FreeBSD/Alpha local DoS Message-ID: <40D83485.3000708@marcetam.net> In-Reply-To: <002601c45856$fea84990$020110ac@mm> References: <002601c45856$fea84990$020110ac@mm>
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> > Hi, Thank you for reply. >The third, actually - but you should talk to alpha@freebsd.org >instead. We do not issue security advisories for local denial of >service vulnerabilities. Ok. Well, I hope you don't maint if I issue it somewhere. (I would just like to hear from Alpha developers, to know they wrote solution for it). >>something like putting : >>#ifdef ALPHA >>#define ALIGNED(x) x << 62 ? 0 : 1 >>#endif >It's not that simple, because alignment requirements exist on other >platforms as well, and usually vary with the type of data. Since argv >and envv are pointers to arrays of pointers, we need to check that >they satisfy the alignment requirements for pointers: >#define PTR_ALIGNED(x) (((x) & 0x7) == 0) I agree. Thank you for pointing this out. >>#ifdef ALPHA >>if (!ALIGNED(*argv) || !ALIGNED(*env)) >>return -ERROR; >>#endif > You need to check argv itself, not what it points to; and "return > -ERROR" is a Linuxism. The correct incantation in FreeBSD would be > > if (!PTR_ALIGNED(uap->argv) || !PTR_ALIGNED(uap->envv)) > return (EFAULT); Sorry for Linuxism, I just didn't pay attention to it. Just wanted to share idea. Of course that formal incantation should be respected. Your line looks like possible workaround. >which should be at the top of execve() in src/sys/kern/kern_exec.c. >Actually, we already have an ALIGNED_POINTER() macro on Alpha, AMD64 >and IA64, but we can't use it in MI code since it doesn't exist on all >platforms. This should be easy to fix. Please correct me if I am wrong, but src/sys/kern/kern_exec.c is MI code. So, putting the macro ALIGNED_POINTER or PTR_ALIGNED into execve(), in mentioned file, whould be actually, putting MD code (since it's not necessary on all platforms), into MI code ? Well, I guess it's easy to fix, but I would just like to hear someone from Alpha developers, to see their final idea, solution and patch for this. Best regards, Milos Marceta
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