5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yousef Alhouseen <redacted>
commit 53637506884dbd5c91a89b1a3547d99d80f8ed2c upstream.
ipmb_write() read message fields before validating the length byte.
A zero or short write can read uninitialized stack bytes.
A length smaller than the SMBus header underflows the block write length.
Require a non-empty buffer and the minimum IPMB request length.
Also require the length byte plus payload before parsing the message.
Fixes: 51bd6f291583 ("Add support for IPMB driver")
Cc: <redacted>
Signed-off-by: Yousef Alhouseen <redacted>
Message-ID: [off-list ref]
Signed-off-by: Corey Minyard <corey@minyard.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/ipmi/ipmb_dev_int.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/ipmi/ipmb_dev_int.c
+++ b/drivers/char/ipmi/ipmb_dev_int.c
@@ -141,13 +141,14 @@ static ssize_t ipmb_write(struct file *f
u8 msg[MAX_MSG_LEN];
ssize_t ret;
- if (count > sizeof(msg))
+ if (!count || count > sizeof(msg))
return -EINVAL;
if (copy_from_user(&msg, buf, count))
return -EFAULT;
- if (count < msg[0])
+ if (msg[IPMB_MSG_LEN_IDX] < IPMB_REQUEST_LEN_MIN ||
+ count < (size_t)msg[IPMB_MSG_LEN_IDX] + 1)
return -EINVAL;
rq_sa = GET_7BIT_ADDR(msg[RQ_SA_8BIT_IDX]);