From: Christian Brauner <brauner@kernel.org>
Date: Mon, 3 Nov 2025 11:26:55 +0000 (+0100)
Subject: backing-file: use credential guards for mmap
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6e1d1c1fa7b1a8d318ccb5f4f64b2a2b5803cf1c;p=thirdparty%2Flinux.git

backing-file: use credential guards for mmap

Use credential guards for scoped credential override with automatic
restoration on scope exit.

Link: https://patch.msgid.link/20251103-work-creds-guards-simple-v1-7-a3e156839e7f@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/backing-file.c b/fs/backing-file.c
index 87ff918320c5..ea137be16331 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -331,7 +331,6 @@ EXPORT_SYMBOL_GPL(backing_file_splice_write);
 int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
 		      struct backing_file_ctx *ctx)
 {
-	const struct cred *old_cred;
 	struct file *user_file = vma->vm_file;
 	int ret;
 
@@ -343,9 +342,8 @@ int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
 
 	vma_set_file(vma, file);
 
-	old_cred = override_creds(ctx->cred);
-	ret = vfs_mmap(vma->vm_file, vma);
-	revert_creds(old_cred);
+	scoped_with_creds(ctx->cred)
+		ret = vfs_mmap(vma->vm_file, vma);
 
 	if (ctx->accessed)
 		ctx->accessed(user_file);