Messages in this thread | | | Date | Tue, 30 Aug 2022 13:53:06 -0700 | Subject | [PATCH 0/3] Fix FORTIFY=y UBSAN_LOCAL_BOUNDS=y | From | Nick Desaulniers <> |
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With CONFIG_FORTIFY=y and CONFIG_UBSAN_LOCAL_BOUNDS=y enabled, we observe a runtime panic while running Android's Compatibility Test Suite's (CTS) android.hardware.input.cts.tests. This is stemming from a strlen() call in hidinput_allocate().
__builtin_object_size(str, 0 or 1) has interesting behavior for C strings when str is runtime dependent, and all possible values are known at compile time; it evaluates to the maximum of those sizes. This causes UBSAN_LOCAL_BOUNDS to insert faults for the smaller values, which we trip at runtime.
Patch 1 adds a KCONFIG version check for __builtin_dynamic_object_size, and uses that in __compiletime_strlen rather than __builtin_object_size. Patch 2 and 3 are cosmetic cleanups, they're not as important to me as patch 1 is.
Nick Desaulniers (3): fortify: use __builtin_dynamic_object_size in __compiletime_strlen fortify: cosmetic cleanups to __compiletime_strlen HID: avoid runtime call to strlen
drivers/hid/hid-input.c | 13 ++++++++++++- include/linux/fortify-string.h | 15 ++++++++++----- init/Kconfig | 3 +++ 3 files changed, 25 insertions(+), 6 deletions(-)
-- 2.37.2.672.g94769d06f0-goog
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