CONFIG_UBSAN_TRAP: Abort on Sanitizer warnings (smaller kernel but less verbose)

General informations

The Linux kernel configuration item CONFIG_UBSAN_TRAP has multiple definitions:

Abort on Sanitizer warnings (smaller kernel but less verbose) found in lib/Kconfig.ubsan

The configuration item CONFIG_UBSAN_TRAP:

• prompt: Abort on Sanitizer warnings (smaller kernel but less verbose)
• type: bool
• depends on: ! CONFIG_COMPILE_TEST
• defined in lib/Kconfig.ubsan
• found in Linux kernels: 6.6–6.8, 6.9-rc+HEAD

Help text

Building kernels with Sanitizer features enabled tends to grow the kernel size by around 5%, due to adding all the debugging text on failure paths. To avoid this, Sanitizer instrumentation can just issue a trap. This reduces the kernel size overhead but turns all warnings (including potentially harmless conditions) into full exceptions that abort the running kernel code (regardless of context, locks held, etc), which may destabilize the system. For some system builders this is an acceptable trade-off.

Also note that selecting Y will cause your kernel to Oops with an "illegal instruction" error with no further details when a UBSAN violation occurs. (Except on arm64, which will report which Sanitizer failed.) This may make it hard to determine whether an Oops was caused by UBSAN or to figure out the details of a UBSAN violation. It makes the kernel log output less useful for bug reports.

On Sanitizer warnings, abort the running kernel code found in lib/Kconfig.ubsan

The configuration item CONFIG_UBSAN_TRAP:

• prompt: On Sanitizer warnings, abort the running kernel code
• type: bool
• depends on: ! CONFIG_COMPILE_TEST
• defined in lib/Kconfig.ubsan
• found in Linux kernels: 5.7–5.19, 6.0–6.5

Help text

Building kernels with Sanitizer features enabled tends to grow the kernel size by around 5%, due to adding all the debugging text on failure paths. To avoid this, Sanitizer instrumentation can just issue a trap. This reduces the kernel size overhead but turns all warnings (including potentially harmless conditions) into full exceptions that abort the running kernel code (regardless of context, locks held, etc), which may destabilize the system. For some system builders this is an acceptable trade-off.

Hardware

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The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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