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From: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
To: casey@schaufler-ca.com
Cc: jmorris@namei.org, serge@hallyn.com, andreyknvl@google.com,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com
Subject: [PATCH] smackfs: restrict bytes count in smackfs write functions
Date: Sun, 24 Jan 2021 20:36:27 +0600	[thread overview]
Message-ID: <20210124143627.582115-1-snovitoll@gmail.com> (raw)

syzbot found WARNINGs in several smackfs write operations where
bytes count is passed to memdup_user_nul which exceeds
GFP MAX_ORDER. Check count size if bigger SMK_LONGLABEL,
for smk_write_syslog if bigger than PAGE_SIZE - 1.

Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
---
 security/smack/smackfs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 5d44b7d258ef..88678c6f1b8c 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -1167,7 +1167,7 @@ static ssize_t smk_write_net4addr(struct file *file, const char __user *buf,
 		return -EPERM;
 	if (*ppos != 0)
 		return -EINVAL;
-	if (count < SMK_NETLBLADDRMIN)
+	if (count < SMK_NETLBLADDRMIN || count > SMK_LONGLABEL)
 		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
@@ -1427,7 +1427,7 @@ static ssize_t smk_write_net6addr(struct file *file, const char __user *buf,
 		return -EPERM;
 	if (*ppos != 0)
 		return -EINVAL;
-	if (count < SMK_NETLBLADDRMIN)
+	if (count < SMK_NETLBLADDRMIN || count > SMK_LONGLABEL)
 		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
@@ -2647,6 +2647,8 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
+	if (count > PAGE_SIZE - 1)
+		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
@@ -2744,6 +2746,8 @@ static ssize_t smk_write_relabel_self(struct file *file, const char __user *buf,
 	 */
 	if (*ppos != 0)
 		return -EINVAL;
+	if (count > SMK_LONGLABEL)
+		return -EINVAL;
 
 	data = memdup_user_nul(buf, count);
 	if (IS_ERR(data))
-- 
2.25.1


             reply	other threads:[~2021-01-24 14:37 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-24 14:36 Sabyrzhan Tasbolatov [this message]
2021-01-25 18:08 ` [PATCH] smackfs: restrict bytes count in smackfs write functions Casey Schaufler
2021-01-25 22:42   ` Tetsuo Handa
2021-01-28 11:58     ` [PATCH v2] " Sabyrzhan Tasbolatov
2021-01-28 12:59       ` Tetsuo Handa
2021-01-28 13:27         ` Sabyrzhan Tasbolatov
2021-01-28 14:24           ` Tetsuo Handa
2021-01-29  2:10             ` Casey Schaufler
2021-02-02 19:13               ` Sabyrzhan Tasbolatov
2021-02-02 19:33                 ` Casey Schaufler

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