From: Jeremy Compostella jeremy.compostella@intel.com

commit 89c6efa61f5709327ecfa24bff18e57a4e80c7fa upstream.

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 data out of the msgbuf1 array boundary.

It is possible from a user application to run into that issue by calling the I2C_SMBUS ioctl with data.block[0] greater than I2C_SMBUS_BLOCK_MAX + 1.

This patch makes the code compliant with Documentation/i2c/dev-interface by raising an error when the requested size is larger than 32 bytes.

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@intel.com Signed-off-by: Wolfram Sang wsa@the-dreams.de Cc: stable@kernel.org [connoro@google.com: 4.4 backport: adjust filename] Signed-off-by: Connor O'Brien connoro@google.com --- drivers/i2c/i2c-core.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index e4587411b447..153376009b46 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -2936,16 +2936,16 @@ 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 %s size %d\n", + read_write == I2C_SMBUS_READ ? "read" : "write", + 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]; }