linux-kernel - [PATCH] wil6210: check len before memcpy() calls

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Message-Id: <20191001120823.29853-1-efremov@linux.com>
Date:   Tue,  1 Oct 2019 15:08:23 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     linux-wireless@...r.kernel.org
Cc:     Denis Efremov <efremov@...ux.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, wil6210@....qualcomm.com,
        Maya Erez <merez@...eaurora.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>, stable@...r.kernel.org
Subject: [PATCH] wil6210: check len before memcpy() calls

memcpy() in wmi_set_ie() and wmi_update_ft_ies() is called with
src == NULL and len == 0. This is an undefined behavior. Fix it
by checking "ie_len > 0" before the memcpy() calls.

As suggested by GCC documentation:
"The pointers passed to memmove (and similar functions in <string.h>)
must be non-null even when nbytes==0, so GCC can use that information
to remove the check after the memmove call." [1]

[1] https://gcc.gnu.org/gcc-4.9/porting_to.html

Cc: Maya Erez <merez@...eaurora.org>
Cc: Kalle Valo <kvalo@...eaurora.org>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: stable@...r.kernel.org
Signed-off-by: Denis Efremov <efremov@...ux.com>
---
 drivers/net/wireless/ath/wil6210/wmi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/wil6210/wmi.c b/drivers/net/wireless/ath/wil6210/wmi.c
index 153b84447e40..41389c1eb252 100644
--- a/drivers/net/wireless/ath/wil6210/wmi.c
+++ b/drivers/net/wireless/ath/wil6210/wmi.c
@@ -2505,7 +2505,8 @@ int wmi_set_ie(struct wil6210_vif *vif, u8 type, u16 ie_len, const void *ie)
 	cmd->mgmt_frm_type = type;
 	/* BUG: FW API define ieLen as u8. Will fix FW */
 	cmd->ie_len = cpu_to_le16(ie_len);
-	memcpy(cmd->ie_info, ie, ie_len);
+	if (ie_len)
+		memcpy(cmd->ie_info, ie, ie_len);
 	rc = wmi_send(wil, WMI_SET_APPIE_CMDID, vif->mid, cmd, len);
 	kfree(cmd);
 out:
@@ -2541,7 +2542,8 @@ int wmi_update_ft_ies(struct wil6210_vif *vif, u16 ie_len, const void *ie)
 	}
 
 	cmd->ie_len = cpu_to_le16(ie_len);
-	memcpy(cmd->ie_info, ie, ie_len);
+	if (ie_len)
+		memcpy(cmd->ie_info, ie, ie_len);
 	rc = wmi_send(wil, WMI_UPDATE_FT_IES_CMDID, vif->mid, cmd, len);
 	kfree(cmd);
 
-- 
2.21.0