linux-kernel - [tip: core/uaccess] scm: Convert put

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <176347611705.498.9194390520921635565.tip-bot2@tip-bot2>
Date: Tue, 18 Nov 2025 14:28:37 -0000
From: "tip-bot2 for Christophe Leroy" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: core/uaccess] scm: Convert put_cmsg() to scoped user access

The following commit has been merged into the core/uaccess branch of tip:

Commit-ID:     1c204914bc4401623a1b242305c583060a0b7e4f
Gitweb:        https://git.kernel.org/tip/1c204914bc4401623a1b242305c583060a0b7e4f
Author:        Christophe Leroy <christophe.leroy@...roup.eu>
AuthorDate:    Mon, 17 Nov 2025 17:43:43 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 18 Nov 2025 15:27:34 +01:00

scm: Convert put_cmsg() to scoped user access

Replace the open coded implementation with the scoped user access guard.

That also corrects the imbalance between masked_user_access_begin() and
user_write_access_end(), which would affect PowerPC when it gains masked
user access support.

No functional change intended.

[ tglx: Amend change log ]

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://patch.msgid.link/793219313f641eda09a892d06768d2837246bf9f.1763396724.git.christophe.leroy@csgroup.eu
---
 net/core/scm.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/net/core/scm.c b/net/core/scm.c
index 66eaee7..cd87f66 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -273,17 +273,13 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
 
 		check_object_size(data, cmlen - sizeof(*cm), true);
 
-		if (can_do_masked_user_access())
-			cm = masked_user_access_begin(cm);
-		else if (!user_write_access_begin(cm, cmlen))
-			goto efault;
-
-		unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
-		unsafe_put_user(level, &cm->cmsg_level, efault_end);
-		unsafe_put_user(type, &cm->cmsg_type, efault_end);
-		unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
-				    cmlen - sizeof(*cm), efault_end);
-		user_write_access_end();
+		scoped_user_write_access_size(cm, cmlen, efault) {
+			unsafe_put_user(cmlen, &cm->cmsg_len, efault);
+			unsafe_put_user(level, &cm->cmsg_level, efault);
+			unsafe_put_user(type, &cm->cmsg_type, efault);
+			unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
+					    cmlen - sizeof(*cm), efault);
+		}
 	} else {
 		struct cmsghdr *cm = msg->msg_control;
 
@@ -301,8 +297,6 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
 	msg->msg_controllen -= cmlen;
 	return 0;
 
-efault_end:
-	user_write_access_end();
 efault:
 	return -EFAULT;
 }