Re: [PATCH] wl1251: Fix possible buffer overflow in wl1251_cmd_scan
From: Kalle Valo <hidden>
Date: 2021-04-18 06:57:34
Also in:
linux-wireless, lkml
Lee Gibson [off-list ref] writes:
Function wl1251_cmd_scan calls memcpy without checking the length. A user could control that length and trigger a buffer overflow. Fix by checking the length is within the maximum allowed size. Signed-off-by: Lee Gibson <redacted>
Please fix the commit log, the user cannot control this length as cfg80211 checks it before handling it to wl1251. Unless I'm missing something.
quoted hunk
--- drivers/net/wireless/ti/wl1251/cmd.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/drivers/net/wireless/ti/wl1251/cmd.c b/drivers/net/wireless/ti/wl1251/cmd.c index 498c8db2eb48..e4d028a53d91 100644 --- a/drivers/net/wireless/ti/wl1251/cmd.c +++ b/drivers/net/wireless/ti/wl1251/cmd.c@@ -455,8 +455,11 @@ int wl1251_cmd_scan(struct wl1251 *wl, u8 *ssid, size_t ssid_len, } cmd->params.ssid_len = ssid_len;
If you are checking the length, you should also check ssid_len here.
- if (ssid)
- memcpy(cmd->params.ssid, ssid, ssid_len);
+ if (ssid) {
+ int len = min_t(int, ssid_len, IEEE80211_MAX_SSID_LEN);
+
+ memcpy(cmd->params.ssid, ssid, len);
+ }Please use clamp_val(). Also another (and IMHO better) way to cleanup this is to provide a pointer to struct cfg80211_ssid, which makes it clear that the length can be trusted and not length checking is not needed. So something like this: int wl1251_cmd_scan(struct wl1251 *wl, const struct cfg80211_ssid *ssid, struct ieee80211_channel *channels[], unsigned int n_channels, unsigned int n_probes) -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches