From c7b8be81fc5506a6f2f9f01a06f6806bcca7d48a Mon Sep 17 00:00:00 2001 From: Jeremy Compostella Date: Wed, 15 Nov 2017 12:31:44 -0700 Subject: [PATCH] i2c: core-smbus: prevent stack corruption on read I2C_BLOCK_DATA 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: [] dump_stack+0x67/0x92 [] panic+0xc5/0x1eb [] ? vprintk_default+0x1f/0x30 [] ? i2cdev_ioctl_smbus+0x303/0x320 [] __stack_chk_fail+0x1b/0x20 [] i2cdev_ioctl_smbus+0x303/0x320 [] i2cdev_ioctl+0x4d/0x1e0 [] do_vfs_ioctl+0x2ba/0x490 [] ? security_file_ioctl+0x43/0x60 [] SyS_ioctl+0x79/0x90 [] entry_SYSCALL_64_fastpath+0x12/0x6a Signed-off-by: Jeremy Compostella Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/i2c-core-smbus.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 10f00a8..e54a9b8 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -396,16 +396,17 @@ 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]; } -- 2.7.4