[PATCH 6.1 091/473] wifi: brcmfmac: pcie: handle randbuf allocation failure

Greg Kroah-Hartman
2024-06-06T14:13:34Z

From: Duoming Zhou <duoming@zju.edu.cn>

[ Upstream commit 316f790ebcf94bdf59f794b7cdea4068dc676d4c ]

The kzalloc() in brcmf_pcie_download_fw_nvram() will return null
if the physical memory has run out. As a result, if we use
get_random_bytes() to generate random bytes in the randbuf, the
null pointer dereference bug will happen.

In order to prevent allocation failure, this patch adds a separate
function using buffer on kernel stack to generate random bytes in
the randbuf, which could prevent the kernel stack from overflow.

Fixes: 91918ce88d9f ("wifi: brcmfmac: pcie: Provide a buffer of random bytes to the device")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240306140437.18177-1-duoming@zju.edu.cn
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../wireless/broadcom/brcm80211/brcmfmac/pcie.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
index 3b1277a8bd617..99cc41135473a 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
@@ -1640,6 +1640,15 @@ struct brcmf_random_seed_footer {
#define BRCMF_RANDOM_SEED_MAGIC 0xfeedc0de
#define BRCMF_RANDOM_SEED_LENGTH 0x100

+static noinline_for_stack void
+brcmf_pcie_provide_random_bytes(struct brcmf_pciedev_info *devinfo, u32 address)
+{
+ u8 randbuf[BRCMF_RANDOM_SEED_LENGTH];
+
+ get_random_bytes(randbuf, BRCMF_RANDOM_SEED_LENGTH);
+ memcpy_toio(devinfo->tcm + address, randbuf, BRCMF_RANDOM_SEED_LENGTH);
+}
+
static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,
const struct firmware *fw, void *nvram,
u32 nvram_len)
@@ -1682,7 +1691,6 @@ static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,
.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
@@ -1694,10 +1702,7 @@ static int brcmf_pcie_download_fw_nvram(struct brcmf_pciedev_info *devinfo,
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);
+ brcmf_pcie_provide_random_bytes(devinfo, address);
}
} else {
brcmf_dbg(PCIE, "No matching NVRAM file found %s\n",
--
2.43.0