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[PATCH] hw: misc: edu: fix 2 off-by-one errors
From: |
Chris Friedt |
Subject: |
[PATCH] hw: misc: edu: fix 2 off-by-one errors |
Date: |
Fri, 14 Oct 2022 12:12:47 -0400 |
In the case that size1 was zero, because of the explicit
'end1 > addr' check, the range check would fail and the error
message would read as shown below. The correct comparison
is 'end1 >= addr' (or 'addr <= end1').
EDU: DMA range 0x40000-0x3ffff out of bounds (0x40000-0x3ffff)!
At the opposite end, in the case that size1 was 4096, within()
would fail because of the non-inclusive check 'end1 < end2',
which should have been 'end1 <= end2'. The error message would
previously say
EDU: DMA range 0x40000-0x40fff out of bounds (0x40000-0x40fff)!
Note: the original change (and error message) was when parameters
were uint32_t.
Signed-off-by: Chris Friedt <chrisfriedt@gmail.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1254
---
hw/misc/edu.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index e935c418d4..a6f5f97f13 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -103,19 +103,18 @@ static void edu_lower_irq(EduState *edu, uint32_t val)
}
}
-static bool within(uint64_t addr, uint64_t start, uint64_t end)
-{
- return start <= addr && addr < end;
-}
-
static void edu_check_range(uint64_t addr, uint64_t size1, uint64_t start,
uint64_t size2)
{
uint64_t end1 = addr + size1;
uint64_t end2 = start + size2;
- if (within(addr, start, end2) &&
- end1 > addr && within(end1, start, end2)) {
+ /*
+ * 1. ensure we aren't overflowing
+ * 2. ensure that [start, end2) is within [addr, end1)
+ */
+ if (end1 >= addr && end2 >= start && start >= addr && end2 <= end1)
+ {
return;
}
--
2.36.1
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