There are actually two bugs here. First, we need to ensure that count
is at least sizeof(u32) or msg.len will be uninitialized data.
The "msg.len" variable is a u32 that comes from the user. On 32bit
systems the "sizeof_field(struct ipmi_ssif_msg, len) + msg.len"
addition can overflow if "msg.len" is greater than U32_MAX - 4.
Valid lengths for "msg.len" are 1-254. Add a check for that to
prevent the integer overflow.
Fixes: dd2bc5cc9e25 ("ipmi: ssif_bmc: Add SSIF BMC driver")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
drivers/char/ipmi/ssif_bmc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
---
drivers/char/ipmi/ssif_bmc.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/char/ipmi/ssif_bmc.c b/drivers/char/ipmi/ssif_bmc.c
index 56346fb32872..ab4e87a99f08 100644
--- a/drivers/char/ipmi/ssif_bmc.c
+++ b/drivers/char/ipmi/ssif_bmc.c
@@ -177,13 +177,15 @@ static ssize_t ssif_bmc_write(struct file *file, const char __user *buf, size_t
unsigned long flags;
ssize_t ret;
- if (count > sizeof(struct ipmi_ssif_msg))
+ if (count < sizeof(msg.len) ||
+ count > sizeof(struct ipmi_ssif_msg))
return -EINVAL;
if (copy_from_user(&msg, buf, count))
return -EFAULT;
- if (!msg.len || count < sizeof_field(struct ipmi_ssif_msg, len) + msg.len)
+ if (!msg.len || msg.len > IPMI_SSIF_PAYLOAD_MAX ||
+ count < sizeof_field(struct ipmi_ssif_msg, len) + msg.len)
return -EINVAL;
spin_lock_irqsave(&ssif_bmc->lock, flags);
--
2.43.0
