[lts86] mptcp: fix race on unaccepted mptcp sockets

[bmastbergen]

jira VULN-52916
cve CVE-2022-49669

commit-author Paolo Abeni <pabeni@redhat.com>
commit 6aeed9045071f2252ff4e98fc13d1e304f33e5b0

When the listener socket owning the relevant request is closed, it frees the unaccepted subflows and that causes later deletion of the paired MPTCP sockets.

The mptcp socket's worker can run in the time interval between such delete operations. When that happens, any access to msk->first will cause an UaF access, as the subflow cleanup did not cleared such field in the mptcp socket.

Address the issue explicitly traversing the listener socket accept queue at close time and performing the needed cleanup on the pending msk.

Note that the locking is a bit tricky, as we need to acquire the msk socket lock, while still owning the subflow socket one.

Fixes: 86e39e04482b ("mptcp: keep track of local endpoint still available for each msk")
	Signed-off-by: Paolo Abeni <pabeni@redhat.com>
	Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
	Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 6aeed9045071f2252ff4e98fc13d1e304f33e5b0)
	Signed-off-by: Brett Mastbergen <bmastbergen@ciq.com>

Build Log

/home/brett/kernel-src-tree
no .config file found, moving on
[TIMER]{MRPROPER}: 0s
x86_64 architecture detected, copying config
'configs/kernel-x86_64.config' -> '.config'
Setting Local Version for build
CONFIG_LOCALVERSION="-bmastbergen_ciqlts8_6_VULN-52916-9ef683bb2a64"
Making olddefconfig
--
  HOSTLD  scripts/kconfig/conf
scripts/kconfig/conf  --olddefconfig Kconfig
#
# configuration written to .config
#
Starting Build
scripts/kconfig/conf  --syncconfig Kconfig
  SYSTBL  arch/x86/include/generated/asm/syscalls_32.h
  SYSHDR  arch/x86/include/generated/asm/unistd_32_ia32.h
  SYSHDR  arch/x86/include/generated/asm/unistd_64_x32.h
  SYSTBL  arch/x86/include/generated/asm/syscalls_64.h
--
  LD [M]  sound/usb/usx2y/snd-usb-usx2y.ko
  LD [M]  sound/x86/snd-hdmi-lpe-audio.ko
  LD [M]  sound/virtio/virtio_snd.ko
  LD [M]  sound/xen/snd_xen_front.ko
  LD [M]  virt/lib/irqbypass.ko
[TIMER]{BUILD}: 957s
Making Modules
  INSTALL arch/x86/crypto/blowfish-x86_64.ko
  INSTALL arch/x86/crypto/camellia-aesni-avx-x86_64.ko
  INSTALL arch/x86/crypto/camellia-aesni-avx2.ko
  INSTALL arch/x86/crypto/camellia-x86_64.ko
--
  INSTALL sound/virtio/virtio_snd.ko
  INSTALL sound/x86/snd-hdmi-lpe-audio.ko
  INSTALL sound/xen/snd_xen_front.ko
  INSTALL virt/lib/irqbypass.ko
  DEPMOD  4.18.0-bmastbergen_ciqlts8_6_VULN-52916-9ef683bb2a64+
[TIMER]{MODULES}: 11s
Making Install
sh ./arch/x86/boot/install.sh 4.18.0-bmastbergen_ciqlts8_6_VULN-52916-9ef683bb2a64+ arch/x86/boot/bzImage \
	System.map "/boot"
[TIMER]{INSTALL}: 105s
Checking kABI
Checking kABI
kABI check passed
Setting Default Kernel to /boot/vmlinuz-4.18.0-bmastbergen_ciqlts8_6_VULN-52916-9ef683bb2a64+ and Index to 2
Hopefully Grub2.0 took everything ... rebooting after time metrices
[TIMER]{MRPROPER}: 0s
[TIMER]{BUILD}: 957s
[TIMER]{MODULES}: 11s
[TIMER]{INSTALL}: 105s
[TIMER]{TOTAL} 1090s
Rebooting in 10 seconds

Testing

kselftests were run before and after applying the fix

selftest-4.18.0-372.32.1.el8_6.86ciq_lts.11.1.x86_64.log

selftest-4.18.0-bmastbergen_ciqlts8_6_VULN-52916-9ef683bb2a64+.log

brett@lycia ~/ciq/vuln-52916 % grep ^ok selftest-4.18.0-372.32.1.el8_6.86ciq_lts.11.1.x86_64.log | wc -l
176
brett@lycia ~/ciq/vuln-52916 % grep ^ok selftest-4.18.0-bmastbergen_ciqlts8_6_VULN-52916-9ef683bb2a64+.log | wc -l
178
brett@lycia ~/ciq/vuln-52916 %

[thefossguy-ciq]

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