Date: Thu, 4 Mar 1999 19:43:40 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Peter Jeremy <peter.jeremy@auss2.alcatel.com.au> Cc: current@FreeBSD.ORG Subject: Re: Simple DOS against 3.x locks box solid Message-ID: <199903050343.TAA37181@apollo.backplane.com> References: <99Mar5.141337est.40405@border.alcanet.com.au>
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:Another interim solution would be to `fix' GNU grep so it doesn't
:attempt to read() into mmap()'d space. (Having not looked at the
:code, I don't know how difficult this would be).
:
:As for the general problem, is it sensible to allow a read-only file to
:be mmap'd R/W (with or without MAP_PRIVATE) and then written into? It
:would be fairly easy to make mmap() return EACCES if the fd was not
:open for writing (or map the memory R/O and SEGV on a write).
:
:I would personally prefer to see a process die with an mmap failure
:(or SIGSEGV), rather than cause a deadlock - ie even if we do want/
:...
We really need to fix the kernel, I think. This sort of deadlock
situation has been a problem for too long and it is only going to
get worse as more programs use mmap().
-Matt
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