Messages in this thread | | | Date | Thu, 21 Jan 2010 17:53:17 +0000 | From | Russell King <> | Subject | Re: Generic DMA - BUG_ON |
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On Thu, Jan 21, 2010 at 09:51:37AM -0600, Steven J. Magnani wrote: > On Wed, 2010-01-20 at 12:00 +0100, Joerg Roedel wrote: > > On Wed, Jan 20, 2010 at 10:53:50AM +0000, Russell King wrote: > > > and ops is NULL, then this code will oops; you will get a full register > > > dump and backtrace. You can use this information along with markup_oops.pl > > > to find out where the problem is. > > > > You can't rely on the oops if the code runs in process context. The > > process may have address 0 mapped which would result in a security hole. > > We had two of these bugs last year. > > You also can't rely on an oops in a NOMMU environment.
I don't see why implementations where NULL pointer derefs should be penalized by having additional NULL checks.
Maybe this needs to be a conditional check which can be optimized away on architectures where NULL dereference always produces an oops.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of:
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