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Jesper Dangaard Brouer 676e4a6fe7 xdp: fix cpumap redirect SKB creation bug We want to avoid leaking pointer info from xdp_frame (that is placed in top of frame) like commit `6dfb970d3d` ("xdp: avoid leaking info stored in frame data on page reuse"), and followup commit `97e19cce05` ("bpf: reserve xdp_frame size in xdp headroom") that reserve this headroom. These changes also affected how cpumap constructed SKBs, as xdpf->headroom size changed, the skb data starting point were in-effect shifted with 32 bytes (sizeof xdp_frame). This was still okay, as the cpumap frame_size calculation also included xdpf->headroom which were reduced by same amount. A bug was introduced in commit `77ea5f4cbe` ("bpf/cpumap: make sure frame_size for build_skb is aligned if headroom isn't"), where the xdpf->headroom became part of the SKB_DATA_ALIGN rounding up. This round-up to find the frame_size is in principle still correct as it does not exceed the 2048 bytes frame_size (which is max for ixgbe and i40e), but the 32 bytes offset of pkt_data_start puts this over the 2048 bytes limit. This cause skb_shared_info to spill into next frame. It is a little hard to trigger, as the SKB need to use above 15 skb_shinfo->frags[] as far as I calculate. This does happen in practise for TCP streams when skb_try_coalesce() kicks in. KASAN can be used to detect these wrong memory accesses, I've seen: BUG: KASAN: use-after-free in skb_try_coalesce+0x3cb/0x760 BUG: KASAN: wild-memory-access in skb_release_data+0xe2/0x250 Driver veth also construct a SKB from xdp_frame in this way, but is not affected, as it doesn't reserve/deduct the room (used by xdp_frame) from the SKB headroom. Instead is clears the pointers via xdp_scrub_frame(), and allows SKB to use this area. The fix in this patch is to do like veth and instead allow SKB to (re)use the area occupied by xdp_frame, by clearing via xdp_scrub_frame(). (This does kill the idea of the SKB being able to access (mem) info from this area, but I guess it was a bad idea anyhow, and it was already killed by the veth changes.) Fixes: `77ea5f4cbe` ("bpf/cpumap: make sure frame_size for build_skb is aligned if headroom isn't") Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>		2019-03-29 12:15:02 -07:00
arch	Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf	2019-03-16 12:20:08 -07:00
block
certs
crypto
Documentation	bpf, doc: fix BTF docs reflow of bullet list	2019-03-26 13:13:42 -07:00
drivers	r8169: fix cable re-plugging issue	2019-03-23 21:26:43 -04:00
fs
include	net/sched: let actions use RCU to access 'goto_chain'	2019-03-21 13:26:42 -07:00
init
ipc
kernel	xdp: fix cpumap redirect SKB creation bug	2019-03-29 12:15:02 -07:00
lib	rhashtable: Still do rehash when we get EEXIST	2019-03-21 13:57:28 -07:00
LICENSES
mm	filemap: pass vm_fault to the mmap ra helpers	2019-03-14 14:36:20 -07:00
net	rxrpc: avoid clang -Wuninitialized warning	2019-03-23 21:48:30 -04:00
samples
scripts
security
sound
tools	bpf, libbpf: fix quiet install_headers	2019-03-28 17:01:37 +01:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2019-03-14 09:28:12 -07:00
Makefile
README

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.