mm/vmalloc.c: fix an overflow bug in alloc_vmap_area()
When searching a vmap area in the vmalloc space, we use (addr + size - 1) to check if the value is less than addr, which is an overflow. But we assign (addr + size) to vmap_area->va_end. So if we come across the below case: (addr + size - 1) : not overflow (addr + size) : overflow we will assign an overflow value (e.g 0) to vmap_area->va_end, And this will trigger BUG in __insert_vmap_area, causing system panic. So using (addr + size) to check the overflow should be the correct behaviour, not (addr + size - 1). Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Reported-by: Ghennadi Procopciuc <unix140@gmail.com> Tested-by: Daniel Baluta <dbaluta@ixiacom.com> Cc: David Rientjes <rientjes@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -388,12 +388,12 @@ nocache:
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addr = ALIGN(first->va_end, align);
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if (addr < vstart)
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goto nocache;
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if (addr + size - 1 < addr)
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if (addr + size < addr)
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goto overflow;
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} else {
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addr = ALIGN(vstart, align);
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if (addr + size - 1 < addr)
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if (addr + size < addr)
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goto overflow;
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n = vmap_area_root.rb_node;
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@ -420,7 +420,7 @@ nocache:
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if (addr + cached_hole_size < first->va_start)
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cached_hole_size = first->va_start - addr;
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addr = ALIGN(first->va_end, align);
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if (addr + size - 1 < addr)
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if (addr + size < addr)
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goto overflow;
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if (list_is_last(&first->list, &vmap_area_list))
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