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Miller" , Jakub Kicinski , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] mwifiex: Fix possible buffer overflows in mwifiex_uap_bss_param_prepare References: <20201208113607.24967-1-ruc_zhangxiaohui@163.com> Date: Tue, 08 Dec 2020 16:28:53 +0200 In-Reply-To: <20201208113607.24967-1-ruc_zhangxiaohui@163.com> (Xiaohui Zhang's message of "Tue, 8 Dec 2020 19:36:07 +0800") Message-ID: <87blf4e5i2.fsf@codeaurora.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Xiaohui Zhang writes: > From: Zhang Xiaohui > > mwifiex_uap_bss_param_prepare() calls memcpy() without checking > the destination size may trigger a buffer overflower, > which a local user could use to cause denial of service or the > execution of arbitrary code. > Fix it by putting the length check before calling memcpy(). > > Signed-off-by: Zhang Xiaohui > --- > drivers/net/wireless/marvell/mwifiex/uap_cmd.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/wireless/marvell/mwifiex/uap_cmd.c b/drivers/net/wireless/marvell/mwifiex/uap_cmd.c > index b48a85d79..fb937c7ee 100644 > --- a/drivers/net/wireless/marvell/mwifiex/uap_cmd.c > +++ b/drivers/net/wireless/marvell/mwifiex/uap_cmd.c > @@ -496,13 +496,16 @@ mwifiex_uap_bss_param_prepare(u8 *tlv, void *cmd_buf, u16 *param_size) > struct mwifiex_ie_types_wmmcap *wmm_cap; > struct mwifiex_uap_bss_param *bss_cfg = cmd_buf; > int i; > + int ssid_size; > u16 cmd_size = *param_size; > > if (bss_cfg->ssid.ssid_len) { > ssid = (struct host_cmd_tlv_ssid *)tlv; > ssid->header.type = cpu_to_le16(TLV_TYPE_UAP_SSID); > ssid->header.len = cpu_to_le16((u16)bss_cfg->ssid.ssid_len); > - memcpy(ssid->ssid, bss_cfg->ssid.ssid, bss_cfg->ssid.ssid_len); > + ssid_size = bss_cfg->ssid.ssid_len > strlen(ssid->ssid) ? > + strlen(ssid->ssid) : bss_cfg->ssid.ssid_len; > + memcpy(ssid->ssid, bss_cfg->ssid.ssid, ssid_size); I think using min_t() is cleaner. Then you would not need to add a temporary variable. -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches