Commit-ID: 3ec979658e5cc0fab86a42af79a650299e4d7135
Gitweb: http://git.kernel.org/tip/3ec979658e5cc0fab86a42af79a650299e4d7135
Author: Wei Yang <richard.weiyang@xxxxxxxxx>
AuthorDate: Sat, 20 Aug 2016 01:40:13 +0000
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 8 Sep 2016 09:11:14 +0200
x86/e820: Fix very large 'size' handling boundary condition
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@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: yinghai@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1471657213-31817-1-git-send-email-richard.weiyang@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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);
--
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