Re: Fwd: LSM patch for Linux-2.4.20-8

From: Valdis.Kletnieks@private
Date: Thu Jan 20 2005 - 21:29:22 PST

On Thu, 20 Jan 2005 18:21:09 PST, Seth Arnold said:

> No, in my experience, tools like stackguard, Solar's non-executable
> stack, and similar, do a great job _finding_ buggy code that would
> otherwise survive in the wild unnoticed for years...

The old-timers among us probably remember the last such flurry of bug-finding,
the "not all the world's a VAX" flurry when Sun shipped their first boxes - and
for about 3-4 years after, bugs kept cropping up in buggy software that tried
to dereference a null pointer - on the Vax systems, page zero was mapped into
the process space, and byte location 0 happened to have a zero in it.  So code

	char *foo = NULL;
	strcpy(dest,foo); /* this happens to clone a null string "for free" */

would suddenly blow chunks on SunOS, because the first page was *not* mapped,
so dereferencing that NULL would earn you a SEGV as quick as that 68020 could
deliver it.

Handing the programmer a SEGV the instant they do something stupid does
wonders.  It's a lot easier to debug that then after everything goes

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