Commit d6bce213 authored by Michael Ellerman's avatar Michael Ellerman Committed by David S. Miller

airo: Fix possible info leak in AIROOLDIOCTL/SIOCDEVPRIVATE

The driver for Cisco Aironet 4500 and 4800 series cards (airo.c),
implements AIROOLDIOCTL/SIOCDEVPRIVATE in airo_ioctl().

The ioctl handler copies an aironet_ioctl struct from userspace, which
includes a command and a length. Some of the commands are handled in
readrids(), which kmalloc()'s a buffer of RIDSIZE (2048) bytes.

That buffer is then passed to PC4500_readrid(), which has two cases.
The else case does some setup and then reads up to RIDSIZE bytes from
the hardware into the kmalloc()'ed buffer.

Here len == RIDSIZE, pBuf is the kmalloc()'ed buffer:

	// read the rid length field
	bap_read(ai, pBuf, 2, BAP1);
	// length for remaining part of rid
	len = min(len, (int)le16_to_cpu(*(__le16*)pBuf)) - 2;
	...
	// read remainder of the rid
	rc = bap_read(ai, ((__le16*)pBuf)+1, len, BAP1);

PC4500_readrid() then returns to readrids() which does:

	len = comp->len;
	if (copy_to_user(comp->data, iobuf, min(len, (int)RIDSIZE))) {

Where comp->len is the user controlled length field.

So if the "rid length field" returned by the hardware is < 2048, and
the user requests 2048 bytes in comp->len, we will leak the previous
contents of the kmalloc()'ed buffer to userspace.

Fix it by kzalloc()'ing the buffer.

Found by Ilja by code inspection, not tested as I don't have the
required hardware.
Reported-by: default avatarIlja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3adb4eaa
......@@ -7813,7 +7813,7 @@ static int readrids(struct net_device *dev, aironet_ioctl *comp) {
return -EINVAL;
}
if ((iobuf = kmalloc(RIDSIZE, GFP_KERNEL)) == NULL)
if ((iobuf = kzalloc(RIDSIZE, GFP_KERNEL)) == NULL)
return -ENOMEM;
PC4500_readrid(ai,ridcode,iobuf,RIDSIZE, 1);
......
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