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wifi: brcmfmac: pcie: handle randbuf allocation failure

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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
This commit is contained in:
Duoming Zhou 2024-03-06 22:04:37 +08:00 committed by Kalle Valo
parent 789c17185f
commit 316f790ebc
1 changed files with 10 additions and 5 deletions
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15
drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c
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@ -1675,6 +1675,15 @@ 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)
@ -1717,7 +1726,6 @@ 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
@ -1729,10 +1737,7 @@ 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",