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util/mmap-alloc: check parameter before using

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Backports commit 4a3ecf201a1a49a804e8506df5906e446707c3b1 from qemu
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Cao jin 2018-03-01 23:53:33 -05:00 committed by Lioncash
parent f424e16f24
commit 217c14ad3e
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 24 additions and 8 deletions
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32
qemu/util/mmap-alloc.c
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@ -12,17 +12,32 @@
#include "qemu/osdep.h"
#include "qemu/mmap-alloc.h"
#include "qemu/host-utils.h"
#include <sys/mman.h>
void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
{
/*
* Note: this always allocates at least one extra page of virtual address
* space, even if size is already aligned.
*/
size_t total = size + align;
void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
/*
* Note: this always allocates at least one extra page of virtual address
* space, even if size is already aligned.
*/
size_t total = size + align;
#if defined(__powerpc64__) && defined(__linux__)
/* On ppc64 mappings in the same segment (aka slice) must share the same
* page size. Since we will be re-allocating part of this segment
* from the supplied fd, we should make sure to use the same page size, to
* this end we mmap the supplied fd. In this case, set MAP_NORESERVE to
* avoid allocating backing store memory.
* We do this unless we are using the system page size, in which case
* anonymous memory is OK.
*/
int anonfd = fd == -1 || qemu_fd_getpagesize(fd) == getpagesize() ? -1 : fd;
int flags = anonfd == -1 ? MAP_ANONYMOUS : MAP_NORESERVE;
void *ptr = mmap(0, total, PROT_NONE, flags | MAP_PRIVATE, anonfd, 0);
#else
void *ptr = mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
#endif
size_t offset;
void *ptr1;
if (ptr == MAP_FAILED) {
@ -30,10 +45,11 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared)
}
/* Make sure align is a power of 2 */
assert(!(align & (align - 1)));
assert(is_power_of_2(align));
/* 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) |