[PATCH 5.16 107/227] brcmfmac: firmware: Fix crash in brcm_alt_fw_path

Greg Kroah-Hartman
2022-02-21T09:53:15Z

From: Phil Elwell <phil@raspberrypi.com>

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@raspberrypi.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220118154514.3245524-1-phil@raspberrypi.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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,