crypto/vmx/p8_ghash memory corruption

[Marcelo Cerri]

That bug was reported on the linux-crypto mailing list by Jan Stancek. The bug is not easily reproduced on Xenial because the crypto API test manager is not enabled and the hash test that exorcises this bug is not present on the Xenial kernel.

---
Hi,

I'm chasing a memory corruption with 4.8-rc7 as I'm observing random Oopses
on ppc BE/LE systems (lpars, KVM guests). About 30% of issues is that
module list gets corrupted, and "cat /proc/modules" or "lsmod" triggers
an Oops, for example:

[ 88.486041] Unable to handle kernel paging request for data at address 0x00000020
...
[ 88.487658] NIP [c00000000020f820] m_show+0xa0/0x240
[ 88.487689] LR [c00000000020f834] m_show+0xb4/0x240
[ 88.487719] Call Trace:
[ 88.487736] [c0000004b605bbb0] [c00000000020f834] m_show+0xb4/0x240 (unreliable)
[ 88.487796] [c0000004b605bc50] [c00000000045e73c] seq_read+0x36c/0x520
[ 88.487843] [c0000004b605bcf0] [c0000000004e1014] proc_reg_read+0x84/0x120
[ 88.487889] [c0000004b605bd30] [c00000000040df88] vfs_read+0xf8/0x380
[ 88.487934] [c0000004b605bde0] [c00000000040fd40] SyS_read+0x60/0x110
[ 88.487981] [c0000004b605be30] [c000000000009590] system_call+0x38/0xec

0x20 offset is module_use->source, module_use is NULL because module.source_list
gets corrupted.

The source of corruption appears to originate from a 'ahash' test for p8_ghash:

cryptomgr_test
 alg_test
  alg_test_hash
   test_hash
    __test_hash
     ahash_partial_update
      shash_async_export
       memcpy

With some extra traces [1], I'm seeing that ahash_partial_update() allocates 56 bytes
for 'state', and then crypto_ahash_export() writes 76 bytes into it:

[ 5.970887] __test_hash alg name p8_ghash, result: c000000004333ac0, key: c0000004b860a500, req: c0000004b860a380
[ 5.970963] state: c000000004333f00, statesize: 56
[ 5.970995] shash_default_export memcpy c000000004333f00 c0000004b860a3e0, len: 76

This seems to directly correspond with:
  p8_ghash_alg.descsize = sizeof(struct p8_ghash_desc_ctx) == 56
  shash_tfm->descsize = sizeof(struct p8_ghash_desc_ctx) + crypto_shash_descsize(fallback) == 56 + 20
where 20 is presumably coming from "ghash_alg.descsize".

My gut feeling was that these 2 should match, but I'd love to hear
what crypto people think.

Thank you,
Jan
---

[Seth Forshee (sforshee)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-xenial' to 'verification-done-xenial'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Seth Forshee (sforshee)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-yakkety' to 'verification-done-yakkety'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.4.0-47.68

---------------
linux (4.4.0-47.68) xenial; urgency=low

  [ Kamal Mostafa ]

  * Release Tracking Bug
    - LP: #1636941

  * Add a driver for Amazon Elastic Network Adapters (ENA) (LP: #1635721)
    - lib/bitmap.c: conversion routines to/from u32 array
    - net: ethtool: add new ETHTOOL_xLINKSETTINGS API
    - net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)
    - [config] enable CONFIG_ENA_ETHERNET=m (Amazon ENA driver)

  * unexpectedly large memory usage of mounted snaps (LP: #1636847)
    - [Config] switch squashfs to single threaded decode

 -- Kamal Mostafa <email address hidden> Wed, 26 Oct 2016 10:47:55 -0700

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.8.0-27.29

---------------
linux (4.8.0-27.29) yakkety; urgency=low

  [ Seth Forshee ]

  * Release Tracking Bug
    - LP: #1635377

  * proc_keys_show crash when reading /proc/keys (LP: #1634496)
    - SAUCE: KEYS: ensure xbuf is large enough to fix buffer overflow in
      proc_keys_show (LP: #1634496)

  * Revert "If zone is so small that watermarks are the same, stop zone balance"
    in yakkety (LP: #1632894)
    - Revert "UBUNTU: SAUCE: (no-up) If zone is so small that watermarks are the
      same, stop zone balance."

  * lts-yakkety 4.8 cannot mount lvm raid1 (LP: #1631298)
    - SAUCE: (no-up) dm raid: fix compat_features validation

  * kswapd0 100% CPU usage (LP: #1518457)
    - SAUCE: (no-up) If zone is so small that watermarks are the same, stop zone
      balance.

  * [Trusty->Yakkety] powerpc/64: Fix incorrect return value from
    __copy_tofrom_user (LP: #1632462)
    - SAUCE: (no-up) powerpc/64: Fix incorrect return value from
      __copy_tofrom_user

  * Ubuntu 16.10: Oops panic in move_page_tables/page_remove_rmap after running
    memory_stress_ng. (LP: #1628976)
    - SAUCE: (no-up) powerpc/pseries: Fix stack corruption in htpe code

  * Paths not failed properly when unmapping virtual FC ports in VIOS (using
    ibmvfc) (LP: #1632116)
    - scsi: ibmvfc: Fix I/O hang when port is not mapped

  * [Ubuntu16.10]KV4.8: kernel livepatch config options are not set
    (LP: #1626983)
    - [Config] Enable live patching on powerpc/ppc64el

  * CONFIG_AUFS_XATTR is not set (LP: #1557776)
    - [Config] CONFIG_AUFS_XATTR=y

  * Yakkety update to 4.8.1 stable release (LP: #1632445)
    - arm64: debug: avoid resetting stepping state machine when TIF_SINGLESTEP
    - Using BUG_ON() as an assert() is _never_ acceptable
    - usb: misc: legousbtower: Fix NULL pointer deference
    - Staging: fbtft: Fix bug in fbtft-core
    - usb: usbip: vudc: fix left shift overflow
    - USB: serial: cp210x: Add ID for a Juniper console
    - Revert "usbtmc: convert to devm_kzalloc"
    - ALSA: hda - Adding one more ALC255 pin definition for headset problem
    - ALSA: hda - Fix headset mic detection problem for several Dell laptops
    - ALSA: hda - Add the top speaker pin config for HP Spectre x360
    - Linux 4.8.1

  * PSL data cache should be flushed before resetting CAPI adapter
    (LP: #1632049)
    - cxl: Flush PSL cache before resetting the adapter

  * thunder nic: avoid link delays due to RX_PACKET_DIS (LP: #1630038)
    - net: thunderx: Don't set RX_PACKET_DIS while initializing

  * crypto/vmx/p8_ghash memory corruption (LP: #1630970)
    - crypto: ghash-generic - move common definitions to a new header file
    - crypto: vmx - Fix memory corruption caused by p8_ghash
    - crypto: vmx - Ensure ghash-generic is enabled

  * arm64: SPCR console not autodetected (LP: #1630311)
    - of/serial: move earlycon early_param handling to serial
    - [Config] CONFIG_ACPI_SPCR_TABLE=y
    - ACPI: parse SPCR and enable matching console
    - ARM64: ACPI: enable ACPI_SPCR_TABLE
    - serial: pl011: add console matching function

  * include/linux/security.h header syntax error with !CONFIG_SECURITYFS
...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.8.0-30.32

---------------
linux (4.8.0-30.32) yakkety; urgency=low

  * CVE-2016-8655 (LP: #1646318)
    - packet: fix race condition in packet_set_ring

 -- Brad Figg <email address hidden> Thu, 01 Dec 2016 08:02:53 -0800