On Wed, Nov 15, 2017 at 12:54:09PM -0700, Compostella, Jeremy wrote:
> On a I2C_SMBUS_I2C_BLOCK_DATA read request, if data->block[0] is
> greater than I2C_SMBUS_BLOCK_MAX + 1, the underlying I2C driver writes
greater or equal?
> data out of the msgbuf1 boundary.
>
> It is possible from a user application to run into that issue by call
> the I2C_SMBUS ioctl with data.block[0] greater than
> I2C_SMBUS_BLOCK_MAX + 1.
ditto?
>
> Call Trace:
> [<ffffffff8139f695>] dump_stack+0x67/0x92
> [<ffffffff811802a4>] panic+0xc5/0x1eb
> [<ffffffff810ecb5f>] ? vprintk_default+0x1f/0x30
> [<ffffffff817456d3>] ? i2cdev_ioctl_smbus+0x303/0x320
> [<ffffffff8109a68b>] __stack_chk_fail+0x1b/0x20
> [<ffffffff817456d3>] i2cdev_ioctl_smbus+0x303/0x320
> [<ffffffff81745aed>] i2cdev_ioctl+0x4d/0x1e0
> [<ffffffff811f761a>] do_vfs_ioctl+0x2ba/0x490
> [<ffffffff81336e43>] ? security_file_ioctl+0x43/0x60
> [<ffffffff811f7869>] SyS_ioctl+0x79/0x90
> [<ffffffff81a22e97>] entry_SYSCALL_64_fastpath+0x12/0x6a
>
> Signed-off-by: Jeremy Compostella <jeremy.compostella@xxxxxxxxx>
> ---
> drivers/i2c/i2c-core-smbus.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> index 10f00a8..f0be621 100644
> --- a/drivers/i2c/i2c-core-smbus.c
> +++ b/drivers/i2c/i2c-core-smbus.c
> @@ -398,6 +398,12 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
> case I2C_SMBUS_I2C_BLOCK_DATA:
> if (read_write == I2C_SMBUS_READ) {
> msg[1].len = data->block[0];
> + if (msg[1].len > I2C_SMBUS_BLOCK_MAX) {
> + dev_err(&adapter->dev,
> + "Invalid block read size %d\n",
> + data->block[0]);
> + return -EINVAL;
> + }
Basically good, yet to make the code easier to read I'd suggest
something like this? Untested, wanted to hear your opinion first.
drivers/i2c/i2c-core-smbus.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 4bb9927afd0106..5fc5ddd965434f 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -397,16 +397,16 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
the underlying bus driver */
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
+ if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+ dev_err(&adapter->dev, "Invalid block size %d\n",
+ data->block[0]);
+ return -EINVAL;
+ }
+
if (read_write == I2C_SMBUS_READ) {
msg[1].len = data->block[0];
} else {
msg[0].len = data->block[0] + 1;
- if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
- dev_err(&adapter->dev,
- "Invalid block write size %d\n",
- data->block[0]);
- return -EINVAL;
- }
for (i = 1; i <= data->block[0]; i++)
msgbuf0[i] = data->block[i];
}
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