lsm: convert security_setselfattr() to use memdup_user()

As suggested by the kernel test robot, memdup_user() is a better
option than the combo of kmalloc()/copy_from_user().

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310270805.2ArE52i5-lkp@intel.com/
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/security/security.c b/security/security.c
index a808fd5eba6d43b8be0d11541ad77857e4918ba4..d7b15ea67c3f51b23bc1d1ec3b35d2d14d80ac21 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -4011,14 +4011,9 @@ int security_setselfattr(unsigned int attr, struct lsm_ctx __user *uctx,
        if (size > PAGE_SIZE)
                return -E2BIG;
 
-       lctx = kmalloc(size, GFP_KERNEL);
-       if (lctx == NULL)
-               return -ENOMEM;
-
-       if (copy_from_user(lctx, uctx, size)) {
-               rc = -EFAULT;
-               goto free_out;
-       }
+       lctx = memdup_user(uctx, size);
+       if (IS_ERR(lctx))
+               return PTR_ERR(lctx);
 
        if (size < lctx->len || size < lctx->ctx_len + sizeof(*lctx) ||
            lctx->len < lctx->ctx_len + sizeof(*lctx)) {