Patch "wifi: brcmfmac: pcie: Provide a buffer of random bytes to the device" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    wifi: brcmfmac: pcie: Provide a buffer of random bytes to the device

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     wifi-brcmfmac-pcie-provide-a-buffer-of-random-bytes-.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2d80ab6c1a691e60eef55217d1bbd202bdc2b09d
Author: Hector Martin <marcan@xxxxxxxxx>
Date:   Tue Feb 14 17:00:34 2023 +0900

    wifi: brcmfmac: pcie: Provide a buffer of random bytes to the device
    
    [ Upstream commit 91918ce88d9fef408bb12c46a27c73d79b604c20 ]
    
    Newer Apple firmwares on chipsets without a hardware RNG require the
    host to provide a buffer of 256 random bytes to the device on
    initialization. This buffer is present immediately before NVRAM,
    suffixed by a footer containing a magic number and the buffer length.
    
    This won't affect chips/firmwares that do not use this feature, so do it
    unconditionally for all Apple platforms (those with an Apple OTP).
    
    Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
    Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
    Reviewed-by: Julian Calaby <julian.calaby@xxxxxxxxx>
    Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230214080034.3828-3-marcan@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
index 067ea019b110a..3b1277a8bd617 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
@@ -13,6 +13,7 @@
 #include <linux/bcma/bcma.h>
 #include <linux/sched.h>
 #include <linux/io.h>
+#include <linux/random.h>
 #include <asm/unaligned.h>
 
 #include <soc.h>
@@ -1631,6 +1632,13 @@ brcmf_pcie_init_share_ram_info(struct brcmf_pciedev_info *devinfo,
 	return 0;
 }
 
+struct brcmf_random_seed_footer {
+	__le32 length;
+	__le32 magic;
+};
+
+#define BRCMF_RANDOM_SEED_MAGIC		0xfeedc0de
+#define BRCMF_RANDOM_SEED_LENGTH	0x100
 
 static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,
 					const struct firmware *fw, void *nvram,
@@ -1667,6 +1675,30 @@ static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,
 			  nvram_len;
 		memcpy_toio(devinfo->tcm + address, nvram, nvram_len);
 		brcmf_fw_nvram_free(nvram);
+
+		if (devinfo->otp.valid) {
+			size_t rand_len = BRCMF_RANDOM_SEED_LENGTH;
+			struct brcmf_random_seed_footer footer = {
+				.length = cpu_to_le32(rand_len),
+				.magic = cpu_to_le32(BRCMF_RANDOM_SEED_MAGIC),
+			};
+			void *randbuf;
+
+			/* Some Apple chips/firmwares expect a buffer of random
+			 * data to be present before NVRAM
+			 */
+			brcmf_dbg(PCIE, "Download random seed\n");
+
+			address -= sizeof(footer);
+			memcpy_toio(devinfo->tcm + address, &footer,
+				    sizeof(footer));
+
+			address -= rand_len;
+			randbuf = kzalloc(rand_len, GFP_KERNEL);
+			get_random_bytes(randbuf, rand_len);
+			memcpy_toio(devinfo->tcm + address, randbuf, rand_len);
+			kfree(randbuf);
+		}
 	} else {
 		brcmf_dbg(PCIE, "No matching NVRAM file found %s\n",
 			  devinfo->nvram_name);