From: Leo Stone <leocstone@gmail.com>
Date: Tue, 17 Dec 2024 18:26:57 +0000 (-0800)
Subject: safesetid: check size of policy writes
X-Git-Tag: v6.14-rc1~166^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f09ff307c7299392f1c88f763299e24bc99811c7;p=thirdparty%2Fkernel%2Flinux.git

safesetid: check size of policy writes

syzbot attempts to write a buffer with a large size to a sysfs entry
with writes handled by handle_policy_update(), triggering a warning
in kmalloc.

Check the size specified for write buffers before allocating.

Reported-by: syzbot+4eb7a741b3216020043a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4eb7a741b3216020043a
Signed-off-by: Leo Stone <leocstone@gmail.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
---

diff --git a/security/safesetid/securityfs.c b/security/safesetid/securityfs.c
index 25310468bcddf..8e1ffd70b18ab 100644
--- a/security/safesetid/securityfs.c
+++ b/security/safesetid/securityfs.c
@@ -143,6 +143,9 @@ static ssize_t handle_policy_update(struct file *file,
 	char *buf, *p, *end;
 	int err;
 
+	if (len >= KMALLOC_MAX_SIZE)
+		return -EINVAL;
+
 	pol = kmalloc(sizeof(struct setid_ruleset), GFP_KERNEL);
 	if (!pol)
 		return -ENOMEM;