Messages in this thread |  | | Subject | Re: [PATCH] megaraid driver fix for 2.5.70 | From | Mark Haverkamp <> | Date | 05 Jun 2003 07:46:31 -0700 |
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On Thu, 2003-06-05 at 07:42, James Bottomley wrote: > On Thu, 2003-06-05 at 10:33, Mark Haverkamp wrote: > > On Thu, 2003-06-05 at 07:07, James Bottomley wrote: > > > On Tue, 2003-06-03 at 10:29, Mark Haverkamp wrote: > > > > A recent change to the megaraid driver to fix some memset calls resulted > > > > in overflowing the arrays being cleared and causing a system panic. > > > > This patch fixes the problem by making sure that the arrays being > > > > cleared are dimensioned to the correct size. The patch has been tested > > > > on osdl's stp machines that have megaraid controllers. > > > > > > This patch doesn't quite look like a fix to me: The megaraid mailboxes > > > are always >16 bytes *but* none of the setting commands is supposed to > > > touch any of the status parts (which begin at byte 15), so I don't see > > > how your patch would prevent a panic. > > > > In the memset cases, what fixed the panic was that the size of the > > raw_mbox automatic was set to 16 and the memset was using > > sizeof(mbox_t). I just increased the size of the raw_mbox so it > > wouldn't be overflowed. It sounds like, from what you are saying, that > > the size of raw_mbox should have been left at 16 and the memset changed > > to fill 16 bytes and not the sizeof(mbox_t). > > Ah, that's what I couldn't find in the source, thanks. > > My observation is that only the first 15 bytes of mbox may be altered by > the user thus, since the issue_scb.. functions copy the mbox anyway, > there's not much point allocating the full mbox (although there's no > harm in doing so). But rather than going back to the 16 byte > allocations and fixing the memset sizes, I think mbox_t should be split > into two pieces (and out and an in, with the issue_scb..() routines only > taking the in part) that way everything can be correctly written in > terms of sizeof. > > I was also separately worried about the memcpy in the issue_scb..() > routines which looks like it will set the mbox->busy parameter > (controlled by the driver) to zero. So I copied Atul to see if this is > a genuine problem or not.
The issue_scb.. functions set the busy parameter to 1 so the memcpy of 16 should be OK. For instance in issue_scb_block, busy is preset in the raw_mbox before the memcpy.
Mark.
> > James -- Mark Haverkamp <markh@osdl.org>
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