From: Christian Brauner <brauner@kernel.org>
Date: Mon, 3 Nov 2025 11:26:54 +0000 (+0100)
Subject: backing-file: use credential guards for splice write
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b688171f910e22d1a32dec24bae8dbecbf2fe395;p=thirdparty%2Flinux.git

backing-file: use credential guards for splice write

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

Link: https://patch.msgid.link/20251103-work-creds-guards-simple-v1-6-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 4d4edf906ef34..87ff918320c54 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -303,7 +303,6 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
 				  size_t len, unsigned int flags,
 				  struct backing_file_ctx *ctx)
 {
-	const struct cred *old_cred;
 	ssize_t ret;
 
 	if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING)))
@@ -316,11 +315,11 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
 	if (ret)
 		return ret;
 
-	old_cred = override_creds(ctx->cred);
-	file_start_write(out);
-	ret = out->f_op->splice_write(pipe, out, &iocb->ki_pos, len, flags);
-	file_end_write(out);
-	revert_creds(old_cred);
+	scoped_with_creds(ctx->cred) {
+		file_start_write(out);
+		ret = out->f_op->splice_write(pipe, out, &iocb->ki_pos, len, flags);
+		file_end_write(out);
+	}
 
 	if (ctx->end_write)
 		ctx->end_write(iocb, ret);