cxl: Fix off by one error allowing subsequent mmap page to be accessed

It was discovered that if a process mmaped their problem state area they
were able to access one page more than expected, potentially allowing
them to access the problem state area of an unrelated process.

This was due to a simple off by one error in the mmap fault handler
introduced in 0712dc7e73e59d79bcead5d5520acf4e9e917e87 ("cxl: Fix issues
when unmapping contexts"), which is fixed in this patch.

Cc: stable@vger.kernel.org
Fixes: 0712dc7e73e5 ("cxl: Fix issues when unmapping contexts")
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 6236d4a1f7ad057eee4b4f2958993897917fc94b..1287148629c0d6f0b6e6066d4c883d8dfaebf9da 100644 (file)
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -113,11 +113,11 @@ static int cxl_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 
        if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
                area = ctx->afu->psn_phys;
-               if (offset > ctx->afu->adapter->ps_size)
+               if (offset >= ctx->afu->adapter->ps_size)
                        return VM_FAULT_SIGBUS;
        } else {
                area = ctx->psn_phys;
-               if (offset > ctx->psn_size)
+               if (offset >= ctx->psn_size)
                        return VM_FAULT_SIGBUS;
        }