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Date: Sat, 18 Jul 2009 19:44:33 +0200 From: Michael Buesch <mb@...sch.de> To: Henrique de Moraes Holschuh <hmh@....eng.br> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH] nvram: Fix root triggerable integer overflow crash On Saturday 18 July 2009 17:09:09 Henrique de Moraes Holschuh wrote: > On Sat, 18 Jul 2009, Michael Buesch wrote: > > This bug probably is exploitable by overwriting the function return address or something > > like that. But let's hope there's no distribution out there with user write permissions > > on the /dev/nvram node. So it's probably only exploitable by root. > > I have seen setups with group-writeable /dev/nvram to support some (old!) > thinkpad utilities. Yes it is crw-rw---- 1 root root on Debian. Are there any setuid programs accessing nvram (like the recent tun/pulseaudio exploit?) > Even if it cannot be exploited for more than a DoS, You can randomly overwrite the kernel stack with the data you write to the device. So I do think it is exploitable, because the char device writer controls the kernel stack completely. However, I do not have an example exploit. > IMO that's still bad > enough to warrant fixing this also on stable kernels if they are vulnerable. > So, does the fix also apply to 2.6.27+ ? If it does, please send it to > stable@...nel.org as well. Yeah I forgot to add stable to CC. -- Greetings, Michael. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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