Return-path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:39157 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753717AbaJMUO3 (ORCPT ); Mon, 13 Oct 2014 16:14:29 -0400 Received: by mail-lb0-f174.google.com with SMTP id p9so6972320lbv.5 for ; Mon, 13 Oct 2014 13:14:27 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D174C992F@AcuExch.aculab.com> References: <1413071551-15372-1-git-send-email-rickard_strandqvist@spectrumdigital.se> <063D6719AE5E284EB5DD2968C1650D6D174C992F@AcuExch.aculab.com> From: Rickard Strandqvist Date: Mon, 13 Oct 2014 22:14:07 +0200 Message-ID: (sfid-20141013_221451_511871_985FEC2A) Subject: Re: [PATCH] net: wireless: brcm80211: brcmfmac: dhd_sdio.c: Cleaning up missing null-terminate in conjunction with strncpy To: David Laight Cc: Brett Rudley , Arend van Spriel , Hante Meuleman , "John W. Linville" , Pieter-Paul Giesberts , Daniel Kim , "linux-wireless@vger.kernel.org" , "brcm80211-dev-list@broadcom.com" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2014-10-13 10:55 GMT+02:00 David Laight : > From: Rickard Strandqvist >> Replacing strncpy with strlcpy to avoid strings that lacks null terminate. >> And changed from using strncpy to strlcpy to simplify code. > > I think you should return an error if the strings get truncated. > Silent truncation is going to lead to issues at some point in the future > (in some places). > >> Signed-off-by: Rickard Strandqvist >> --- >> drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c | 25 ++++++++++---------- >> 1 file changed, 12 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c >> b/drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c >> index f55f625..d20d4e6 100644 >> --- a/drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c >> +++ b/drivers/net/wireless/brcm80211/brcmfmac/dhd_sdio.c >> @@ -670,7 +670,6 @@ static int brcmf_sdio_get_fwnames(struct brcmf_chip *ci, >> struct brcmf_sdio_dev *sdiodev) >> { >> int i; >> - uint fw_len, nv_len; >> char end; >> >> for (i = 0; i < ARRAY_SIZE(brcmf_fwname_data); i++) { >> @@ -684,25 +683,25 @@ static int brcmf_sdio_get_fwnames(struct brcmf_chip *ci, >> return -ENODEV; >> } >> >> - fw_len = sizeof(sdiodev->fw_name) - 1; >> - nv_len = sizeof(sdiodev->nvram_name) - 1; >> /* check if firmware path is provided by module parameter */ >> if (brcmf_firmware_path[0] != '\0') { >> - strncpy(sdiodev->fw_name, brcmf_firmware_path, fw_len); >> - strncpy(sdiodev->nvram_name, brcmf_firmware_path, nv_len); >> - fw_len -= strlen(sdiodev->fw_name); >> - nv_len -= strlen(sdiodev->nvram_name); >> + strlcpy(sdiodev->fw_name, brcmf_firmware_path, >> + sizeof(sdiodev->fw_name)); >> + strlcpy(sdiodev->nvram_name, brcmf_firmware_path, >> + sizeof(sdiodev->nvram_name)); >> >> end = brcmf_firmware_path[strlen(brcmf_firmware_path) - 1]; > > If you are doing a strlen() here, you could use the length for the copy > and/or use it to avoid the strcat(). > >> if (end != '/') { >> - strncat(sdiodev->fw_name, "/", fw_len); >> - strncat(sdiodev->nvram_name, "/", nv_len); >> - fw_len--; >> - nv_len--; >> + strlcat(sdiodev->fw_name, "/", >> + sizeof(sdiodev->fw_name)); >> + strlcat(sdiodev->nvram_name, "/", >> + sizeof(sdiodev->nvram_name)); >> } >> } >> - strncat(sdiodev->fw_name, brcmf_fwname_data[i].bin, fw_len); >> - strncat(sdiodev->nvram_name, brcmf_fwname_data[i].nv, nv_len); >> + strlcat(sdiodev->fw_name, brcmf_fwname_data[i].bin, >> + sizeof(sdiodev->fw_name)); >> + strlcat(sdiodev->nvram_name, brcmf_fwname_data[i].nv, >> + sizeof(sdiodev->nvram_name)); > > I assume something ensures that fw_name[0] == 0 here. > > David Hi David What do you mean you would use the strlen, can you give some example code instead? Arend van Spriel wanted me to change the title before. So this should really continue the conversation in that new mail. And then you can also see my other comments. And I have the same type of objection to the: brcmf_firmware_path[0] == '\0' Se: https://lkml.org/lkml/2014/10/12/42 Kind regards Rickard Strandqvist