diff options
| author | Anders Roxell <anders.roxell@linaro.org> | 2019-03-07 16:30:16 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-07 18:32:02 -0800 |
| commit | 1a6a1dbeb72fce7517665b365085ea405490c2d5 (patch) | |
| tree | e485878f879abac0c03ab366352bfee1cfc2aa61 | |
| parent | 663cb6340c6e84fe29aa6d0fa63d85ea6bd6cd19 (diff) | |
lib/ubsan: default UBSAN_ALIGNMENT to not set
When booting an allmodconfig kernel, there are a lot of false-positives.
With a message like this 'UBSAN: Undefined behaviour in...' with a call
trace that follows.
UBSAN warnings are a result of enabling noisy CONFIG_UBSAN_ALIGNMENT
which is disabled by default if HAVE_EFFICIENT_UNALIGNED_ACCESS=y.
It's noisy even if don't have efficient unaligned access, e.g. people
often add __cacheline_aligned_in_smp in structs, but forget to align
allocations of such struct (kmalloc() give 8-byte alignment in worst
case).
Rework so that when building a allmodconfig kernel that turns everything
into '=m' or '=y' will turn off UBSAN_ALIGNMENT.
[aryabinin@virtuozzo.com: changelog addition]
Link: http://lkml.kernel.org/r/20181217150326.30933-1-anders.roxell@linaro.org
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | lib/Kconfig.ubsan | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index 98fa559ebd80..a2ae4a8e4fa6 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -27,15 +27,19 @@ config UBSAN_SANITIZE_ALL Enabling this option will get kernel image size increased significantly. -config UBSAN_ALIGNMENT - bool "Enable checking of pointers alignment" +config UBSAN_NO_ALIGNMENT + bool "Disable checking of pointers alignment" depends on UBSAN - default y if !HAVE_EFFICIENT_UNALIGNED_ACCESS + default y if HAVE_EFFICIENT_UNALIGNED_ACCESS help - This option enables detection of unaligned memory accesses. - Enabling this option on architectures that support unaligned + This option disables the check of unaligned memory accesses. + This option should be used when building allmodconfig. + Disabling this option on architectures that support unaligned accesses may produce a lot of false positives. +config UBSAN_ALIGNMENT + def_bool !UBSAN_NO_ALIGNMENT + config TEST_UBSAN tristate "Module for testing for undefined behavior detection" depends on m && UBSAN |