boundary condition bug fix for vmalloc()

Hi,

Under heavy load conditions, get_vm_area() might end up allocating an address range beyond VMALLOC_END. The problem is after the for loop in get_vm_area() terminates, no consistency check (addr > VMALLOC_END
- size) is performed on the "addr".

I believe the following patch will fix the problem:

@@ -161,11 +161,11 @@
        for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {
                if (size + addr < (unsigned long) tmp->addr)
                        break;
+               addr = tmp->size + (unsigned long) tmp->addr;
                if (addr > VMALLOC_END-size) {
                        kfree(area);
                        return NULL;
                }
-               addr = tmp->size + (unsigned long) tmp->addr;
        }
        area->addr = (void *)addr;
        area->size = size + PAGE_SIZE;

Please let me know if this patch is pulled into the source tree, so I can update my tree.

Thanks.

Kanoj
[email protected]
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Hi,

Agreed, and the patch looks OK. Moving the test outside the for loop entirely has the same effect while shaving a few cycles off the function. The existing clearly broken in not checking the size of the final area if we ran off the end of the vm_area chain.

--Stephen

----------------------------------------------------------------

@@ -161,11 +161,11 @@
 	for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {
 		if (size + addr < (unsigned long) tmp->addr)
 			break;
-		if (addr > VMALLOC_END-size) {
-			kfree(area);
-			return NULL;
-		}
 		addr = tmp->size + (unsigned long) tmp->addr;
+	}
+	if (addr > VMALLOC_END-size) {
+		kfree(area);
+		return NULL;
 	}
 	area->addr = (void *)addr;
 	area->size = size + PAGE_SIZE;

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