From: Phil Elwell <phil@xxxxxxxxxxxxxxx> commit 665408f4c3a5c83e712871daa062721624b2b79e upstream. The call to brcm_alt_fw_path in brcmf_fw_get_firmwares is not protected by a check to the validity of the fwctx->req->board_type pointer. This results in a crash in strlcat when, for example, the WLAN chip is found in a USB dongle. Prevent the crash by adding the necessary check. See: https://github.com/raspberrypi/linux/issues/4833 Fixes: 5ff013914c62 ("brcmfmac: firmware: Allow per-board firmware binaries") Signed-off-by: Phil Elwell <phil@xxxxxxxxxxxxxxx> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220118154514.3245524-1-phil@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c @@ -693,7 +693,7 @@ int brcmf_fw_get_firmwares(struct device { struct brcmf_fw_item *first = &req->items[0]; struct brcmf_fw *fwctx; - char *alt_path; + char *alt_path = NULL; int ret; brcmf_dbg(TRACE, "enter: dev=%s\n", dev_name(dev)); @@ -712,7 +712,9 @@ int brcmf_fw_get_firmwares(struct device fwctx->done = fw_cb; /* First try alternative board-specific path if any */ - alt_path = brcm_alt_fw_path(first->path, fwctx->req->board_type); + if (fwctx->req->board_type) + alt_path = brcm_alt_fw_path(first->path, + fwctx->req->board_type); if (alt_path) { ret = request_firmware_nowait(THIS_MODULE, true, alt_path, fwctx->dev, GFP_KERNEL, fwctx,
