xattr: switch to CLASS(fd)

commit a71874379ec8c6e788a61d71b3ad014a8d9a5c08 upstream.

BUG=b/492102770
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2024-14027 in the Linux kernel.

cos-patch: security-moderate
Reviewed-by: Christian Brauner <brauner@kernel.org>
Change-Id: If9f28e0909f150c74c0d80d1b595a0575ebefe6f
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/141203
Reviewed-by: Kevin Liu <zhihuil@google.com>
Reviewed-by: Chenglong Tang <chenglongtang@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>

fs/xattr.c

diff --git a/fs/xattr.c b/fs/xattr.c
index 0191ac25..23b9e4b 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -697,9 +697,9 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
 	int error;
 
 	CLASS(fd, f)(fd);
-	if (!fd_file(f))
-		return -EBADF;
 
+	if (fd_empty(f))
+		return -EBADF;
 	audit_file(fd_file(f));
 	error = setxattr_copy(name, &ctx);
 	if (error)
@@ -809,16 +809,13 @@ SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
 SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
 		void __user *, value, size_t, size)
 {
-	struct fd f = fdget(fd);
-	ssize_t error = -EBADF;
+	CLASS(fd, f)(fd);
 
-	if (!fd_file(f))
-		return error;
+	if (fd_empty(f))
+		return -EBADF;
 	audit_file(fd_file(f));
-	error = getxattr(file_mnt_idmap(fd_file(f)), fd_file(f)->f_path.dentry,
+	return getxattr(file_mnt_idmap(fd_file(f)), fd_file(f)->f_path.dentry,
 			 name, value, size);
-	fdput(f);
-	return error;
 }
 
 /*
@@ -885,15 +882,12 @@ SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
 
 SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
 {
-	struct fd f = fdget(fd);
-	ssize_t error = -EBADF;
+	CLASS(fd, f)(fd);
 
-	if (!fd_file(f))
-		return error;
+	if (fd_empty(f))
+		return -EBADF;
 	audit_file(fd_file(f));
-	error = listxattr(fd_file(f)->f_path.dentry, list, size);
-	fdput(f);
-	return error;
+	return listxattr(fd_file(f)->f_path.dentry, list, size);
 }
 
 /*
@@ -950,12 +944,12 @@ SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
 
 SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
 {
-	struct fd f = fdget(fd);
+	CLASS(fd, f)(fd);
 	char kname[XATTR_NAME_MAX + 1];
-	int error = -EBADF;
+	int error;
 
-	if (!fd_file(f))
-		return error;
+	if (fd_empty(f))
+		return -EBADF;
 	audit_file(fd_file(f));
 
 	error = strncpy_from_user(kname, name, sizeof(kname));
@@ -970,7 +964,6 @@ SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
 				    fd_file(f)->f_path.dentry, kname);
 		mnt_drop_write_file(fd_file(f));
 	}
-	fdput(f);
 	return error;
 }