Commit e265cfa1 authored Oct 13, 2007 by David Brownell Committed by Jean Delvare Oct 13, 2007

i2c-dev: Reject I2C_M_RECV_LEN



The I2C_M_RECV_LEN calling convention for i2c_mesg.flags involves
playing games with reported buffer lengths.  (They start out less
than their actual size, and the length is then modified to reflect
how many bytes were delivered ... which one hopes is less than the
presumed actual size.)  Refuse to play such error prone games across
the boundary between userspace and kernel.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

parent 9d90c1fd

drivers/i2c/i2c-dev.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -226,8 +226,10 @@ static int i2cdev_ioctl(struct inode inode, struct file file,

		res = 0;
		for( i=0; i<rdwr_arg.nmsgs; i++ ) {
		/* Limit the size of the message to a sane amount */
		if (rdwr_pa[i].len > 8192) {
		/* Limit the size of the message to a sane amount;
		* and don't let length change either. */
		if ((rdwr_pa[i].len > 8192) \|\|
		(rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
		res = -EINVAL;
		break;
		}

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