linux-kernel - [PATCH] bna: prevent bad user input in bnad_debugfs_write

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Message-Id: <20251030053411.710-1-linmq006@gmail.com>
Date: Thu, 30 Oct 2025 13:34:10 +0800
From: Miaoqian Lin <linmq006@...il.com>
To: Rasesh Mody <rmody@...vell.com>,
	Sudarsana Kalluru <skalluru@...vell.com>,
	GR-Linux-NIC-Dev@...vell.com,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Ivan Vecera <ivecera@...hat.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: linmq006@...il.com,
	stable@...r.kernel.org
Subject: [PATCH] bna: prevent bad user input in bnad_debugfs_write_regrd()

A malicious user could pass an arbitrarily bad value
to memdup_user_nul(), potentially causing kernel crash.

This follows the same pattern as commit ee76746387f6
("netdevsim: prevent bad user input in nsim_dev_health_break_write()")
and commit 7ef4c19d245f
("smackfs: restrict bytes count in smackfs write functions")

Found via static analysis and code review.

Fixes: d0e6a8064c42 ("bna: use memdup_user to copy userspace buffers")
Cc: stable@...r.kernel.org
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
 drivers/net/ethernet/brocade/bna/bnad_debugfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/brocade/bna/bnad_debugfs.c b/drivers/net/ethernet/brocade/bna/bnad_debugfs.c
index 8f0972e6737c..ad33ab1d266d 100644
--- a/drivers/net/ethernet/brocade/bna/bnad_debugfs.c
+++ b/drivers/net/ethernet/brocade/bna/bnad_debugfs.c
@@ -311,6 +311,9 @@ bnad_debugfs_write_regrd(struct file *file, const char __user *buf,
 	unsigned long flags;
 	void *kern_buf;
 
+	if (nbytes == 0 || nbytes > PAGE_SIZE)
+		return -EINVAL;
+
 	/* Copy the user space buf */
 	kern_buf = memdup_user_nul(buf, nbytes);
 	if (IS_ERR(kern_buf))
-- 
2.39.5 (Apple Git-154)