From "Jason A. Donenfeld" <> Subject [PATCH 0/4] ozwpan: Four remote packet-of-death vulnerabilities Date Wed, 13 May 2015 20:33:30 +0200 The ozwpan driver accepts network packets, parses them, and converts

them into various USB functionality. There are numerous security

vulnerabilities in the handling of these packets. Two of them result in

a memcpy(kernel_buffer, network_packet, -length), one of them is a

divide-by-zero, and one of them is a loop that decrements -1 until it's

zero.



I've written a very simple proof-of-concept for each one of these

vulnerabilities to aid with detecting and fixing them. The general

operation of each proof-of-concept code is:



- Load the module with:

# insmod ozwpan.ko g_net_dev=eth0

- Compile the PoC with ozprotocol.h from the kernel tree:

$ cp /path/to/linux/drivers/staging/ozwpan/ozprotocol.h ./

$ gcc ./poc.c -o ./poc

- Run the PoC:

# ./poc eth0 [mac-address]



These PoCs should also be useful to the maintainers for testing out

constructing and sending various other types of malformed packets against

which this driver should be hardened.



Please assign CVEs for these vulnerabilities. I believe the first two

patches of this set can receive one CVE for both, and the remaining two

can receive one CVE each.





On a slightly related note, there are several other vulnerabilities in

this driver that are worth looking into. When ozwpan receives a packet,

it casts the packet into a variety of different structs, based on the

value of type and length parameters inside the packet. When making these

casts, and when reading bytes based on this length parameter, the actual

length of the packet in the socket buffer is never actually consulted. As

such, it's very likely that a packet could be sent that results in the

kernel reading memory in adjacent buffers, resulting in an information

leak, or from unpaged addresses, resulting in a crash. In the former case,

it may be possible with certain message types to actually send these

leaked adjacent bytes back to the sender of the packet. So, I'd highly

recommend the maintainers of this driver go branch-by-branch from the

initial rx function, adding checks to ensure all reads and casts are

within the bounds of the socket buffer.



Jason A. Donenfeld (4):

ozwpan: Use proper check to prevent heap overflow

ozwpan: Use unsigned ints to prevent heap overflow

ozwpan: divide-by-zero leading to panic

ozwpan: unchecked signed subtraction leads to DoS



drivers/staging/ozwpan/ozhcd.c | 8 ++++----

drivers/staging/ozwpan/ozusbif.h | 4 ++--

drivers/staging/ozwpan/ozusbsvc1.c | 11 +++++++++--

3 files changed, 15 insertions(+), 8 deletions(-)



--

2.3.6







