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Filename Latest commit message Latest commit date
Pavel Skripkin 527feae56f net: llc: fix skb_over_panic
[ Upstream commit c7c9d2102c9c098916ab9e0ab248006107d00d6c ]

Syzbot reported skb_over_panic() in llc_pdu_init_as_xid_cmd(). The
problem was in wrong LCC header manipulations.

Syzbot's reproducer tries to send XID packet. llc_ui_sendmsg() is
doing following steps:

	1. skb allocation with size = len + header size
		len is passed from userpace and header size
		is 3 since addr->sllc_xid is set.

	2. skb_reserve() for header_len = 3
	3. filling all other space with memcpy_from_msg()

Ok, at this moment we have fully loaded skb, only headers needs to be
filled.

Then code comes to llc_sap_action_send_xid_c(). This function pushes 3
bytes for LLC PDU header and initializes it. Then comes
llc_pdu_init_as_xid_cmd(). It initalizes next 3 bytes *AFTER* LLC PDU
header and call skb_push(skb, 3). This looks wrong for 2 reasons:

	1. Bytes rigth after LLC header are user data, so this function
	   was overwriting payload.

	2. skb_push(skb, 3) call can cause skb_over_panic() since
	   all free space was filled in llc_ui_sendmsg(). (This can
	   happen is user passed 686 len: 686 + 14 (eth header) + 3 (LLC
	   header) = 703. SKB_DATA_ALIGN(703) = 704)

So, in this patch I added 2 new private constansts: LLC_PDU_TYPE_U_XID
and LLC_PDU_LEN_U_XID. LLC_PDU_LEN_U_XID is used to correctly reserve
header size to handle LLC + XID case. LLC_PDU_TYPE_U_XID is used by
llc_pdu_header_init() function to push 6 bytes instead of 3. And finally
I removed skb_push() call from llc_pdu_init_as_xid_cmd().

This changes should not affect other parts of LLC, since after
all steps we just transmit buffer.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+5e5a981ad7cc54c4b2b4@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-08-04 12:27:39 +02:00
arch x86/kvm: fix vcpu-id indexed array sizes 2021-08-04 12:27:37 +02:00
block rq-qos: fix missed wake-ups in rq_qos_throttle try two 2021-07-19 08:53:16 +02:00
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto crypto: shash - avoid comparing pointers to exported functions under CFI 2021-07-14 16:53:13 +02:00
Documentation userfaultfd: do not untag user pointers 2021-07-28 13:31:01 +02:00
drivers mlx4: Fix missing error code in mlx4_load_one() 2021-08-04 12:27:39 +02:00
fs ocfs2: issue zeroout to EOF blocks 2021-08-04 12:27:37 +02:00
include net: llc: fix skb_over_panic 2021-08-04 12:27:39 +02:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc
kernel cgroup1: fix leaked context root causing sporadic NULL deref in LTP 2021-07-31 08:19:37 +02:00
lib lib/decompress_unlz4.c: correctly handle zero-padding around initrds. 2021-07-20 16:10:46 +02:00
LICENSES
mm mm: slab: fix kmem_cache_create failed when sysfs node not destroyed 2021-07-25 14:35:14 +02:00
net net: llc: fix skb_over_panic 2021-08-04 12:27:39 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:53:30 +02:00
scripts kbuild: mkcompile_h: consider timestamp if KBUILD_BUILD_TIMESTAMP is set 2021-07-25 14:35:12 +02:00
security smackfs: restrict bytes count in smk_set_cipso() 2021-07-19 08:53:18 +02:00
sound ALSA: hdmi: Expose all pins on MSI MS-7C94 board 2021-07-28 13:30:59 +02:00
tools tools: Allow proper CC/CXX/... override with LLVM=1 in Makefile.include 2021-07-31 08:19:37 +02:00
usr
virt KVM: add missing compat KVM_CLEAR_DIRTY_LOG 2021-08-04 12:27:37 +02:00
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.cocciconfig
.get_maintainer.ignore
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.gitignore
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COPYING
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Makefile Linux 5.4.137 2021-07-31 08:19:39 +02:00
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