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SubjectRE: [PATCH] net: wireless: brcm80211: brcmfmac: dhd_sdio.c: Cleaning up missing null-terminate in conjunction with strncpy
Date
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 <rickard_strandqvist@spectrumdigital.se>
> ---
> 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





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