linux-kernel - [PATCH 3/3] vfs: shave a branch in getname

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Date: Tue,  4 Jun 2024 17:52:57 +0200
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org
Cc: viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH 3/3] vfs: shave a branch in getname_flags

Check for an error while copying and no path in one branch.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---
 fs/namei.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 950ad6bdd9fe..f25dcb9077dd 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -148,9 +148,20 @@ getname_flags(const char __user *filename, int flags)
 	result->name = kname;
 
 	len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
-	if (unlikely(len < 0)) {
-		__putname(result);
-		return ERR_PTR(len);
+	/*
+	 * Handle both empty path and copy failure in one go.
+	 */
+	if (unlikely(len <= 0)) {
+		if (unlikely(len < 0)) {
+			__putname(result);
+			return ERR_PTR(len);
+		}
+
+		/* The empty path is special. */
+		if (!(flags & LOOKUP_EMPTY)) {
+			__putname(result);
+			return ERR_PTR(-ENOENT);
+		}
 	}
 
 	/*
@@ -188,14 +199,6 @@ getname_flags(const char __user *filename, int flags)
 	}
 
 	atomic_set(&result->refcnt, 1);
-	/* The empty path is special. */
-	if (unlikely(!len)) {
-		if (!(flags & LOOKUP_EMPTY)) {
-			putname(result);
-			return ERR_PTR(-ENOENT);
-		}
-	}
-
 	result->uptr = filename;
 	result->aname = NULL;
 	audit_getname(result);
-- 
2.39.2