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[Qemu-devel] [PULL 05/15] oslib: allocate PROT_NONE pages on top of RAM
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PULL 05/15] oslib: allocate PROT_NONE pages on top of RAM |
Date: |
Fri, 2 Oct 2015 16:45:19 +0300 |
This inserts a read and write protected page between RAM and QEMU
memory. This makes it harder to exploit QEMU bugs resulting from buffer
overflows in devices using variants of cpu_physical_memory_map,
dma_memory_map etc.
Signed-off-by: Michael S. Tsirkin <address@hidden>
Reviewed-by: Paolo Bonzini <address@hidden>
Acked-by: Paolo Bonzini <address@hidden>
---
util/oslib-posix.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 27972d4..a0fcdc2 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -128,7 +128,7 @@ void *qemu_memalign(size_t alignment, size_t size)
void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
{
size_t align = QEMU_VMALLOC_ALIGN;
- size_t total = size + align - getpagesize();
+ 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;
void *ptr1;
@@ -154,8 +154,8 @@ void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
if (offset > 0) {
munmap(ptr - offset, offset);
}
- if (total > size) {
- munmap(ptr + size, total - size);
+ if (total > size + getpagesize()) {
+ munmap(ptr + size + getpagesize(), total - size - getpagesize());
}
trace_qemu_anon_ram_alloc(size, ptr);
@@ -172,7 +172,7 @@ void qemu_anon_ram_free(void *ptr, size_t size)
{
trace_qemu_anon_ram_free(ptr, size);
if (ptr) {
- munmap(ptr, size);
+ munmap(ptr, size + getpagesize());
}
}
--
MST
- [Qemu-devel] [PULL 00/15] virtio,pc features, fixes, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 01/15] virtio: introduce virtqueue_unmap_sg(), Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 06/15] exec: allocate PROT_NONE pages on top of RAM, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 08/15] virtio: Notice when the system doesn't support MSIx at all, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 11/15] vhost-user: unit test for new messages, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 12/15] memhp: extend address auto assignment to support gaps, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 07/15] pc: Add a comment explaining why pc_compat_2_4() doesn't exist, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 03/15] virtio-net: correctly drop truncated packets, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 05/15] oslib: allocate PROT_NONE pages on top of RAM,
Michael S. Tsirkin <=
- [Qemu-devel] [PULL 10/15] vhost-user-test: do not reinvent glib-compat.h, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 13/15] pc: memhp: force gaps between DIMM's GPA, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 02/15] virtio: introduce virtqueue_discard(), Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 09/15] virtio-9p: migrate virtio subsections, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 04/15] oslib: rework anonimous RAM allocation, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 15/15] vhost-user-test: fix predictable filename on tmpfs, Michael S. Tsirkin, 2015/10/08
- [Qemu-devel] [PULL 14/15] vhost-user-test: use tmpfs by default, Michael S. Tsirkin, 2015/10/08