[U-Boot] [PATCH v2 00/13] Import Undefined Behavior Sanitizer

[Eugeniu Rosca]

While certain classes of bugs (e.g. locking related) are totally
irrelevant for U-Boot, undefined behavior is something U-Boot may
experience all over the place and this certainly can lead to hidden
and difficult to debug issues.

As of v4.18, Linux kernel contains roughly 119 UBSAN fixes [1], so it
has been quite a productive and useful tool to play with during
development.

Thanks to UBSAN, this series fixes 11 (+1 in [2]) UB issues, revealed
by simply cold-booting (sometimes by running an existing command on)
sandbox, qemu-system-{arm,ppc,i386} and arm64 R-Car Gen3 targets.

  | Undefined Behavior class              | Noticed | Fixed | Ref
--|---------------------------------------|---------|-------|-----
A | Signed shift overflow                 | 8       | 8     |
B | Zero-sized array declaration          | 2       | 2     |
C | Read-past-end-of-array                | 1       | 1     |
D | Shift by negative value               | 1       | 0     | [3]
E | Load of address 'X' with insufficient |         |       |
  |      space for an object of type 'Y'  | ~20-30  | 0     | [4]

A certain class of UBs (see E above) is reported regularly at runtime
on all architectures and looks to be related to the implementation of
U-Boot linker-generated arrays [4]. I believe some feedback from the
authors/maintainers of those is required to assess if this is a UBSAN
false positive or a real bug.

The "signed shift overflow" (see A above) UB is very common in U-Boot.
Grepping the code for '(1 << 31)' (which is a consistent source of this
type of UB) gives 528 occurrences:
$ git grep -E '1[ ]*<<[ ]*31' | wc -l
  528

This series collects the low-hanging fruit, as well as leaves others to
experiment with UBSAN themselves.

Best regards,
Eugeniu.

[1] git log --oneline --no-merges --grep UBSAN v4.18 | wc -l
    119
[2] https://patchwork.ozlabs.org/patch/957323/

[3] Example of "shift by negative value" UB
 ==================================================================
 UBSAN: Undefined behaviour in drivers/pci/fsl_pci_init.c:139:17
 shift exponent -1 is negative
 ==================================================================

[4] Either a false-positive or a bug in "include/linker_lists.h":
 =================================================================
 UBSAN: Undefined behaviour in drivers/core/lists.c:28:26
 load of address 000000000075f180 with insufficient space
 for an object of type 'char *'
 =================================================================

Eugeniu Rosca (13):
  UBSAN: run-time undefined behavior sanity checker
  mmc: Fix signed shift overflow
  armv8: mmu: Fix signed shift overflow
  pinctrl: renesas: Fix signed shift overflow
  net: phy: Fix signed shift overflow
  net: ravb: Fix signed shift overflow
  x86: Fix signed shift overflow in MSR_IA32_APICBASE_BASE
  disk: part_dos: Fix signed shift overflow
  common.h: Fix signed shift overflow in cpumask_next()
  mmc: Fix read-past-end-of-array
  hashtable: Fix zero-sized array
  input: Fix zero-sized array
  configs: sandbox*: Enable UBSAN

 Makefile                           |   3 +-
 arch/Kconfig                       |   4 +
 arch/arm/Kconfig                   |   1 +
 arch/arm/include/asm/armv8/mmu.h   |  42 +--
 arch/x86/include/asm/msr-index.h   |   2 +-
 configs/sandbox64_defconfig        |   1 +
 configs/sandbox_defconfig          |   1 +
 configs/sandbox_flattree_defconfig |   1 +
 configs/sandbox_noblk_defconfig    |   1 +
 configs/sandbox_spl_defconfig      |   1 +
 disk/part_dos.c                    |   9 +-
 drivers/input/input.c              |   4 +-
 drivers/mmc/mmc.c                  |   4 +-
 drivers/net/phy/phy.c              |   4 +-
 drivers/net/ravb.c                 |  16 +-
 drivers/pinctrl/renesas/sh_pfc.h   |  14 +-
 examples/standalone/Makefile       |   2 +
 include/common.h                   |   2 +-
 include/linux/compat.h             |   3 +
 include/search.h                   |   2 +-
 lib/Kconfig                        |   1 +
 lib/Kconfig.ubsan                  |  29 ++
 lib/Makefile                       |   2 +
 lib/hashtable.c                    |   4 +-
 lib/linux_compat.c                 |   3 +
 lib/ubsan.c                        | 461 +++++++++++++++++++++++++++++
 lib/ubsan.h                        |  94 ++++++
 scripts/Makefile.lib               |   6 +
 scripts/Makefile.ubsan             |  20 ++
 29 files changed, 684 insertions(+), 53 deletions(-)
 create mode 100644 lib/Kconfig.ubsan
 create mode 100644 lib/ubsan.c
 create mode 100644 lib/ubsan.h
 create mode 100644 scripts/Makefile.ubsan

-- 
2.18.0