[PATCH net-next v9 0/5] skb_to_sgvec hardening

From: Jason A. Donenfeld
Date: Tue May 23 2017 - 12:06:10 EST


The recent bug with macsec and historical one with virtio have
indicated that letting skb_to_sgvec trounce all over an sglist
without checking the length is probably a bad idea. And it's not
necessary either: an sglist already explicitly marks its last
item, and the initialization functions are diligent in doing so.
Thus there's a clear way of avoiding future overflows.

So, this patchset, from a high level, makes skb_to_sgvec return
a potential error code, and then adjusts all callers to check
for the error code. There are two situations in which skb_to_sgvec
might return such an error:

1) When the passed in sglist is too small; and
2) When the passed in skbuff is too deeply nested.

So, the first patch in this series handles the issues with
skb_to_sgvec directly, and the remaining ones then handle the call
sites.

Changes v8->v9:
- Return correct errno in rxrpc, thanks to feedback from Dave Howells.

Jason A. Donenfeld (5):
skbuff: return -EMSGSIZE in skb_to_sgvec to prevent overflow
ipsec: check return value of skb_to_sgvec always
rxrpc: check return value of skb_to_sgvec always
macsec: check return value of skb_to_sgvec always
virtio_net: check return value of skb_to_sgvec always

drivers/net/macsec.c | 13 ++++++++--
drivers/net/virtio_net.c | 9 +++++--
include/linux/skbuff.h | 8 +++---
net/core/skbuff.c | 65 +++++++++++++++++++++++++++++++-----------------
net/ipv4/ah4.c | 8 ++++--
net/ipv4/esp4.c | 20 +++++++++------
net/ipv6/ah6.c | 8 ++++--
net/ipv6/esp6.c | 20 +++++++++------
net/rxrpc/rxkad.c | 19 ++++++++++----
9 files changed, 116 insertions(+), 54 deletions(-)

--
2.13.0