i2c: core-smbus: prevent stack corruption on read I2C_BLOCK_DATA
authorJeremy Compostella <jeremy.compostella@intel.com>
Wed, 15 Nov 2017 19:31:44 +0000 (12:31 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 23 Jan 2018 18:58:17 +0000 (19:58 +0100)
commitc7b8be81fc5506a6f2f9f01a06f6806bcca7d48a
tree378ffcfa98d1d0a941d335cb328a709fa0608400
parent41812e400fc0f6aa2ff4fde54462b32b2c9884f6
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:
 [<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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/i2c/i2c-core-smbus.c