netdev - [PATCH AUTOSEL 5.4 16/18] wifi: iwlwifi: pcie: Fix integer overflow in iwl_write_to_user

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Message-Id: <20230504195042.3808716-16-sashal@kernel.org>
Date: Thu,  4 May 2023 15:50:38 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Hyunwoo Kim <imv4bel@...il.com>,
	Gregory Greenman <gregory.greenman@...el.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Sasha Levin <sashal@...nel.org>,
	kvalo@...nel.org,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	avraham.stern@...el.com,
	benjamin.berg@...el.com,
	emmanuel.grumbach@...el.com,
	linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 16/18] wifi: iwlwifi: pcie: Fix integer overflow in iwl_write_to_user_buf

From: Hyunwoo Kim <imv4bel@...il.com>

[ Upstream commit 58d1b717879bfeabe09b35e41ad667c79933eb2e ]

An integer overflow occurs in the iwl_write_to_user_buf() function,
which is called by the iwl_dbgfs_monitor_data_read() function.

static bool iwl_write_to_user_buf(char __user *user_buf, ssize_t count,
				  void *buf, ssize_t *size,
				  ssize_t *bytes_copied)
{
	int buf_size_left = count - *bytes_copied;

	buf_size_left = buf_size_left - (buf_size_left % sizeof(u32));
	if (*size > buf_size_left)
		*size = buf_size_left;

If the user passes a SIZE_MAX value to the "ssize_t count" parameter,
the ssize_t count parameter is assigned to "int buf_size_left".
Then compare "*size" with "buf_size_left" . Here, "buf_size_left" is a
negative number, so "*size" is assigned "buf_size_left" and goes into
the third argument of the copy_to_user function, causing a heap overflow.

This is not a security vulnerability because iwl_dbgfs_monitor_data_read()
is a debugfs operation with 0400 privileges.

Signed-off-by: Hyunwoo Kim <imv4bel@...il.com>
Signed-off-by: Gregory Greenman <gregory.greenman@...el.com>
Link: https://lore.kernel.org/r/20230414130637.2d80ace81532.Iecfba549e0e0be21bbb0324675392e42e75bd5ad@changeid
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/intel/iwlwifi/pcie/trans.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
index 8915030030c4c..2f6bcf5e5ac0c 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
@@ -2831,7 +2831,7 @@ static bool iwl_write_to_user_buf(char __user *user_buf, ssize_t count,
 				  void *buf, ssize_t *size,
 				  ssize_t *bytes_copied)
 {
-	int buf_size_left = count - *bytes_copied;
+	ssize_t buf_size_left = count - *bytes_copied;
 
 	buf_size_left = buf_size_left - (buf_size_left % sizeof(u32));
 	if (*size > buf_size_left)
-- 
2.39.2