[PATCH 62/64] hw/rdma: Fix possible mremap overflow in the pvrdma device (CVE-2021-3582)

[Michael Roth]

From: Marcel Apfelbaum <marcel@redhat.com>

Ensure mremap boundaries not trusting the guest kernel to
pass the correct buffer length.

Fixes: CVE-2021-3582
Reported-by: VictorV (Kunlun Lab) <vv474172261@gmail.com>
Tested-by: VictorV (Kunlun Lab) <vv474172261@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Message-Id: <20210616110600.20889-1-marcel.apfelbaum@gmail.com>
Reviewed-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
Tested-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
Reviewed-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
(cherry picked from commit 284f191b4abad213aed04cb0458e1600fd18d7c4)
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 hw/rdma/vmw/pvrdma_cmd.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/rdma/vmw/pvrdma_cmd.c b/hw/rdma/vmw/pvrdma_cmd.c
index f59879e257..da7ddfa548 100644
--- a/hw/rdma/vmw/pvrdma_cmd.c
+++ b/hw/rdma/vmw/pvrdma_cmd.c
@@ -38,6 +38,13 @@ static void *pvrdma_map_to_pdir(PCIDevice *pdev, uint64_t 
pdir_dma,
         return NULL;
     }
 
+    length = ROUND_UP(length, TARGET_PAGE_SIZE);
+    if (nchunks * TARGET_PAGE_SIZE != length) {
+        rdma_error_report("Invalid nchunks/length (%u, %lu)", nchunks,
+                          (unsigned long)length);
+        return NULL;
+    }
+
     dir = rdma_pci_dma_map(pdev, pdir_dma, TARGET_PAGE_SIZE);
     if (!dir) {
         rdma_error_report("Failed to map to page directory");
-- 
2.25.1