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[Qemu-trivial] [PATCH v2] util/mmap-alloc: check parameter before using
From: |
Cao jin |
Subject: |
[Qemu-trivial] [PATCH v2] util/mmap-alloc: check parameter before using |
Date: |
Wed, 26 Oct 2016 19:12:49 +0800 |
Also refactor a little for readability
Signed-off-by: Cao jin <address@hidden>
---
util/mmap-alloc.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 5a85aa3..a32ee53 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -61,7 +61,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool
shared)
#else
void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
#endif
- size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
+ size_t offset;
void *ptr1;
if (ptr == MAP_FAILED) {
@@ -73,6 +73,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool
shared)
/* Always align to host page size */
assert(align >= getpagesize());
+ offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
ptr1 = mmap(ptr + offset, size, PROT_READ | PROT_WRITE,
MAP_FIXED |
(fd == -1 ? MAP_ANONYMOUS : 0) |
@@ -83,22 +84,20 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool
shared)
return MAP_FAILED;
}
- ptr += offset;
- total -= offset;
-
if (offset > 0) {
- munmap(ptr - offset, offset);
+ munmap(ptr, offset);
}
/*
* Leave a single PROT_NONE page allocated after the RAM block, to serve as
* a guard page guarding against potential buffer overflows.
*/
+ total -= offset;
if (total > size + getpagesize()) {
- munmap(ptr + size + getpagesize(), total - size - getpagesize());
+ munmap(ptr1 + size + getpagesize(), total - size - getpagesize());
}
- return ptr;
+ return ptr1;
}
void qemu_ram_munmap(void *ptr, size_t size)
--
2.1.0
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