[PATCH 1/2] Fix segfault in mmio subpage handling code.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

It is possible that subpage mmio is registered over existing memory
page. When this happens "memory" will have real memory address and not
index into io_mem array so next access to the page will generate
segfault. It is uncommon to have some part of a page to be accessed as
memory and some as mmio, but qemu shouldn't crash even when guest does
stupid things. So lets just pretend that the rest of the page is
unassigned if guest configure part of the memory page as mmio.

Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
 exec.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/exec.c b/exec.c
index 5e9a5b7..5945496 100644
--- a/exec.c
+++ b/exec.c
@@ -3363,6 +3363,8 @@ static int subpage_register (subpage_t *mmio, uint32_t start, uint32_t end,
            mmio, start, end, idx, eidx, memory);
     memory = (memory >> IO_MEM_SHIFT) & (IO_MEM_NB_ENTRIES - 1);
+    if ((memory & ~TARGET_PAGE_MASK) == IO_MEM_RAM)
+        memory = IO_MEM_UNASSIGNED;
     for (; idx <= eidx; idx++) {
         mmio->sub_io_index[idx] = memory;
         mmio->region_offset[idx] = region_offset;

To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Photo]     [Yosemite News]    [Yosemite Photos]    [POF Sucks]     [Linux Kernel]     [Linux SCSI]     [XFree86]

Add to Google Powered by Linux