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[PATCH 19/32] afs: Use mem_to_flex_dup() with struct afs_acl



As part of the work to perform bounds checking on all memcpy() uses,
replace the open-coded a deserialization of bytes out of memory into a
trailing flexible array by using a flex_array.h helper to perform the
allocation, bounds checking, and copying.

Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Cc: linux-afs@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 fs/afs/internal.h | 4 ++--
 fs/afs/xattr.c    | 7 ++-----
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 7a72e9c60423..83014d20b6b3 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1125,8 +1125,8 @@ extern bool afs_fs_get_capabilities(struct afs_net *, 
struct afs_server *,
 extern void afs_fs_inline_bulk_status(struct afs_operation *);
 
 struct afs_acl {
-       u32     size;
-       u8      data[];
+       DECLARE_FLEX_ARRAY_ELEMENTS_COUNT(u32, size);
+       DECLARE_FLEX_ARRAY_ELEMENTS(u8, data);
 };
 
 extern void afs_fs_fetch_acl(struct afs_operation *);
diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
index 7751b0b3f81d..77b3af283d49 100644
--- a/fs/afs/xattr.c
+++ b/fs/afs/xattr.c
@@ -73,16 +73,13 @@ static int afs_xattr_get_acl(const struct xattr_handler 
*handler,
 static bool afs_make_acl(struct afs_operation *op,
                         const void *buffer, size_t size)
 {
-       struct afs_acl *acl;
+       struct afs_acl *acl = NULL;
 
-       acl = kmalloc(sizeof(*acl) + size, GFP_KERNEL);
-       if (!acl) {
+       if (mem_to_flex_dup(&acl, buffer, size, GFP_KERNEL)) {
                afs_op_nomem(op);
                return false;
        }
 
-       acl->size = size;
-       memcpy(acl->data, buffer, size);
        op->acl = acl;
        return true;
 }
-- 
2.32.0




 


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