linux-kernel - [for-linus][PATCH 2/2] tracing: Prevent bad count for tracing_cpumask

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Message-ID: <20241225024557.131467576@goodmis.org>
Date: Tue, 24 Dec 2024 21:45:38 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 stable@...r.kernel.org,
 syzbot+0aecfd34fb878546f3fd@...kaller.appspotmail.com,
 Lizhi Xu <lizhi.xu@...driver.com>
Subject: [for-linus][PATCH 2/2] tracing: Prevent bad count for tracing_cpumask_write

From: Lizhi Xu <lizhi.xu@...driver.com>

If a large count is provided, it will trigger a warning in bitmap_parse_user.
Also check zero for it.

Cc: stable@...r.kernel.org
Fixes: 9e01c1b74c953 ("cpumask: convert kernel trace functions")
Link: https://lore.kernel.org/20241216073238.2573704-1-lizhi.xu@windriver.com
Reported-by: syzbot+0aecfd34fb878546f3fd@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0aecfd34fb878546f3fd
Tested-by: syzbot+0aecfd34fb878546f3fd@...kaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@...driver.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/trace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 957f941a08e7..f8aebcb01e62 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5087,6 +5087,9 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
 	cpumask_var_t tracing_cpumask_new;
 	int err;
 
+	if (count == 0 || count > KMALLOC_MAX_SIZE)
+		return -EINVAL;
+
 	if (!zalloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
 		return -ENOMEM;
 
-- 
2.45.2