Messages in this thread Patch in this message | | | Date | Wed, 31 Aug 2016 22:30:41 +0000 | From | Wei Yang <> | Subject | Re: [PATCH] x86/e820: set end to (start + size - 1) in __append_e820_map() |
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Hi, All,
Is my understanding correct?
On Sat, Aug 20, 2016 at 01:40:13AM +0000, Wei Yang wrote: >The (start, size) tuple represents a range [start, start + size - 1], >which means "start" and "start + size - 1" should be compared to see >whether the range overflows. > >For example, a range with (start, size) > > (0xffffffff fffffff0, 0x00000000 00000010) > >represents > > [0xffffffff fffffff0, 0xffffffff ffffffff] > >would be judged overflow in the original code, while actually it is not. > >This patch fixes this and makes sure it still works when size is zero. > >Signed-off-by: Wei Yang <richard.weiyang@gmail.com> >--- > arch/x86/kernel/e820.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > >diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c >index 621b501..871f186 100644 >--- a/arch/x86/kernel/e820.c >+++ b/arch/x86/kernel/e820.c >@@ -388,11 +388,11 @@ static int __init __append_e820_map(struct e820entry *biosmap, int nr_map) > while (nr_map) { > u64 start = biosmap->addr; > u64 size = biosmap->size; >- u64 end = start + size; >+ u64 end = start + size - 1; > u32 type = biosmap->type; > > /* Overflow in 64 bits? Ignore the memory map. */ >- if (start > end) >+ if (start > end && likely(size)) > return -1; > > e820_add_region(start, size, type); >-- >1.7.9.5
-- Wei Yang Help you, Help me
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