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authorOleg Nesterov <oleg@redhat.com>2010-11-30 19:55:34 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2010-12-01 01:56:37 (GMT)
commit3c77f845722158206a7209c45ccddc264d19319c (patch)
tree9eace97a8b88eb68b7d5d3127041b14c202421ae /README
parent37a09f07459753e7c98d4e21f1c61e8756923f81 (diff)
downloadlinux-3c77f845722158206a7209c45ccddc264d19319c.tar.xz
exec: make argv/envp memory visible to oom-killer
Brad Spengler published a local memory-allocation DoS that evades the OOM-killer (though not the virtual memory RLIMIT): http://www.grsecurity.net/~spender/64bit_dos.c execve()->copy_strings() can allocate a lot of memory, but this is not visible to oom-killer, nobody can see the nascent bprm->mm and take it into account. With this patch get_arg_page() increments current's MM_ANONPAGES counter every time we allocate the new page for argv/envp. When do_execve() succeds or fails, we change this counter back. Technically this is not 100% correct, we can't know if the new page is swapped out and turn MM_ANONPAGES into MM_SWAPENTS, but I don't think this really matters and everything becomes correct once exec changes ->mm or fails. Reported-by: Brad Spengler <spender@grsecurity.net> Reviewed-and-discussed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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