From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

The both the size and base of a media sanitize operation are both provided
by the VM, an overflow is possible which may result in checks on valid
range passing when they should not.  Close that by checking for overflow
on the addition.

Fixes: 40ab4ed10775 ("hw/cxl/cxl-mailbox-utils: Media operations Sanitize and Write Zeros commands CXL r3.2(8.2.10.9.5.3)")
Closes: https://lore.kernel.org/qemu-devel/CAFEAcA8Rqop+ju0fuxN+0T57NBG+bep80z45f6pY0ci2fz_G3A@mail.gmail.com/
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20260102154731.474859-2-Jonathan.Cameron@huawei.com>
(cherry picked from commit 87f8e5a71d061964c9bfa4d6e02db47f54dd61f7)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 68c7cc9891..03fbc9a9d1 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -1875,7 +1875,7 @@ static uint64_t get_dc_size(CXLType3Dev *ct3d, MemoryRegion **dc_mr)
 static int validate_dpa_addr(CXLType3Dev *ct3d, uint64_t dpa_addr,
                              size_t length)
 {
-    uint64_t vmr_size, pmr_size, dc_size;
+    uint64_t vmr_size, pmr_size, dc_size, dpa_end;
 
     if ((dpa_addr % CXL_CACHE_LINE_SIZE) ||
         (length % CXL_CACHE_LINE_SIZE)  ||
@@ -1887,7 +1887,12 @@ static int validate_dpa_addr(CXLType3Dev *ct3d, uint64_t dpa_addr,
     pmr_size = get_pmr_size(ct3d, NULL);
     dc_size = get_dc_size(ct3d, NULL);
 
-    if (dpa_addr + length > vmr_size + pmr_size + dc_size) {
+    /* sanitize 64 bit values coming from guest */
+    if (uadd64_overflow(dpa_addr, length, &dpa_end)) {
+        return -EINVAL;
+    }
+
+    if (dpa_end > vmr_size + pmr_size + dc_size) {
         return -EINVAL;
     }
 
-- 
2.47.3