The lkdtm selftest config fragment enables CONFIG_UBSAN_TRAP to make the ARRAY_BOUNDS test kill the calling process when an out-of-bound access is detected by UBSAN. However, after this [1] commit, UBSAN is triggered under many new scenarios that weren't detected before, such as in struct definitions with fixed-size trailing arrays used as flexible arrays. As a result, CONFIG_UBSAN_TRAP=y has become a very aggressive option to enable except for specific situations.
`make kselftest-merge` applies CONFIG_UBSAN_TRAP=y to the kernel config for all selftests, which makes many of them fail because of system hangs during boot.
This change removes the config option from the lkdtm kselftest and also the ARRAY_BOUNDS test to skip it rather than have it failing. If out-of-bound array accesses need to be checked, there's CONFIG_TEST_UBSAN for that.
[1] commit 2d47c6956ab3 ("ubsan: Tighten UBSAN_BOUNDS on GCC")'
Signed-off-by: Ricardo Cañuelo ricardo.canuelo@collabora.com --- tools/testing/selftests/lkdtm/config | 1 - tools/testing/selftests/lkdtm/tests.txt | 2 +- 2 files changed, 1 insertion(+), 2 deletions(-)
diff --git a/tools/testing/selftests/lkdtm/config b/tools/testing/selftests/lkdtm/config index 5d52f64dfb43..7afe05e8c4d7 100644 --- a/tools/testing/selftests/lkdtm/config +++ b/tools/testing/selftests/lkdtm/config @@ -9,7 +9,6 @@ CONFIG_INIT_ON_FREE_DEFAULT_ON=y CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y CONFIG_UBSAN=y CONFIG_UBSAN_BOUNDS=y -CONFIG_UBSAN_TRAP=y CONFIG_STACKPROTECTOR_STRONG=y CONFIG_SLUB_DEBUG=y CONFIG_SLUB_DEBUG_ON=y diff --git a/tools/testing/selftests/lkdtm/tests.txt b/tools/testing/selftests/lkdtm/tests.txt index 607b8d7e3ea3..6a49f2abbda8 100644 --- a/tools/testing/selftests/lkdtm/tests.txt +++ b/tools/testing/selftests/lkdtm/tests.txt @@ -7,7 +7,7 @@ EXCEPTION #EXHAUST_STACK Corrupts memory on failure #CORRUPT_STACK Crashes entire system on success #CORRUPT_STACK_STRONG Crashes entire system on success -ARRAY_BOUNDS +#ARRAY_BOUNDS Needs CONFIG_UBSAN_TRAP=y, might cause unrelated system hangs CORRUPT_LIST_ADD list_add corruption CORRUPT_LIST_DEL list_del corruption STACK_GUARD_PAGE_LEADING
On Tue, Aug 01, 2023 at 11:43:29AM +0200, Ricardo Cañuelo wrote:
The lkdtm selftest config fragment enables CONFIG_UBSAN_TRAP to make the ARRAY_BOUNDS test kill the calling process when an out-of-bound access is detected by UBSAN. However, after this [1] commit, UBSAN is triggered under many new scenarios that weren't detected before, such as in struct definitions with fixed-size trailing arrays used as flexible arrays. As a result, CONFIG_UBSAN_TRAP=y has become a very aggressive option to enable except for specific situations.
Yeah, that's fair. We need to actually get these issues reported and TRAP doesn't help with that.
`make kselftest-merge` applies CONFIG_UBSAN_TRAP=y to the kernel config for all selftests, which makes many of them fail because of system hangs during boot.
This change removes the config option from the lkdtm kselftest and also the ARRAY_BOUNDS test to skip it rather than have it failing. If out-of-bound array accesses need to be checked, there's CONFIG_TEST_UBSAN for that.
I *think* instead, we can turn off TRAP but retain the ARRAY_BOUNDS kselftest by looking for either WARN or TRAP results:
-ARRAY_BOUNDS +ARRAY_BOUNDS call trace:|UBSAN: array-index-out-of-bounds
Can test that and send a v2?
-Kees
Hi Kees,
Thanks for reviewing the patch,
On mar, ago 01 2023 at 17:26:44, Kees Cook keescook@chromium.org wrote:
I *think* instead, we can turn off TRAP but retain the ARRAY_BOUNDS kselftest by looking for either WARN or TRAP results:
-ARRAY_BOUNDS +ARRAY_BOUNDS call trace:|UBSAN: array-index-out-of-bounds
Can test that and send a v2?
Good idea! Sure, I can test it and I'll send v2 in a while.
Cheers, Ricardo
linux-kselftest-mirror@lists.linaro.org
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Kees Cook -
Ricardo Cañuelo