usercopy: Handle vm_map_ram() areas

vmalloc does not allocate a vm_struct for vm_map_ram() areas.  That causes
us to deny usercopies from those areas.  This affects XFS which uses
vm_map_ram() for its directories.

Fix this by calling find_vmap_area() instead of find_vm_area().

Fixes: 60ad8ce18223 ("mm/usercopy: Detect vmalloc overruns")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Tested-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220612213227.3881769-2-willy@infradead.org

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index b159c278996128036f30b2bcbe8a51a3fa6aac3d..096d48aa3437330b7274d06fff48348195147da4 100644 (file)
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -215,6 +215,7 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size,
 void free_vm_area(struct vm_struct *area);
 extern struct vm_struct *remove_vm_area(const void *addr);
 extern struct vm_struct *find_vm_area(const void *addr);
+struct vmap_area *find_vmap_area(unsigned long addr);
 
 static inline bool is_vm_area_hugepages(const void *addr)
 {

diff --git a/mm/usercopy.c b/mm/usercopy.c
index baeacc735b83f98cab991cbdc1fdecd9d213fcd9..cd4b41d9bf76007f4aca9ad5a618a5f1956f026b 100644 (file)
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -173,16 +173,14 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
        }
 
        if (is_vmalloc_addr(ptr)) {
-               struct vm_struct *area = find_vm_area(ptr);
+               struct vmap_area *area = find_vmap_area((unsigned long)ptr);
                unsigned long offset;
 
-               if (!area) {
+               if (!area)
                        usercopy_abort("vmalloc", "no area", to_user, 0, n);
-                       return;
-               }
 
-               offset = ptr - area->addr;
-               if (offset + n > get_vm_area_size(area))
+               offset = (unsigned long)ptr - area->va_start;
+               if ((unsigned long)ptr + n > area->va_end)
                        usercopy_abort("vmalloc", NULL, to_user, offset, n);
                return;
        }

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 07db42455dd4d85b207ae3d7011dea39badf5a5b..effd1ff6a4b412995392de23a956a88f5a9a4074 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1798,7 +1798,7 @@ static void free_unmap_vmap_area(struct vmap_area *va)
        free_vmap_area_noflush(va);
 }
 
-static struct vmap_area *find_vmap_area(unsigned long addr)
+struct vmap_area *find_vmap_area(unsigned long addr)
 {
        struct vmap_area *va;