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[PATCH] x86_64: Fix off by one in bad_addr checking in find_e820_area

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From: Robert Hentosh <robert_hentosh@dell.com>

Actually, we just stumbled on a different bug found in find_e820_area() in
e820.c.  The following code does not handle the edge condition correctly:

   while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size)
       ;
   last = addr + size;
   if ( last > ei->addr + ei->size )
       continue;

The second statement in the while loop needs to be a <= b so that it is the
logical negavite of the if (a > b) outside it. It needs to read:

   while (bad_addr(&addr, size) && addr+size <= ei->addr + ei->size)
       ;

In the case that failed bad_addr was returning an address that is exactly size
bellow the end of the e820 range.

AK: Again together with the earlier avoid edma fix this fixes
boot on a Dell PE6850/16GB

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Robert Hentosh 2006-05-30 22:48:00 +02:00 committed by Linus Torvalds
parent 0d01532451
commit 7ca97c6131
1 changed files with 1 additions and 1 deletions
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2
arch/x86_64/kernel/e820.c
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@ -149,7 +149,7 @@ unsigned long __init find_e820_area(unsigned long start, unsigned long end, unsi
addr = start; addr = start;
if (addr > ei->addr + ei->size) if (addr > ei->addr + ei->size)
continue; continue;
while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size) while (bad_addr(&addr, size) && addr+size <= ei->addr+ei->size)
; ;
last = addr + size; last = addr + size;
if (last > ei->addr + ei->size) if (last > ei->addr + ei->size)