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| author | Thomas Gleixner <tglx@linutronix.de> | 2021-10-21 15:55:06 -0700 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-10-26 10:18:09 +0200 |
| commit | 3aac3ebea08f2d342364f827c8979ab0e1dd591e (patch) | |
| tree | 66cfbec408ebb30544063cde4b49094da02c6d66 /arch/x86/Kconfig | |
| parent | 1bdda24c4af64cd2d65dec5192ab624c5fee7ca0 (diff) | |
| download | lwn-3aac3ebea08f2d342364f827c8979ab0e1dd591e.tar.gz lwn-3aac3ebea08f2d342364f827c8979ab0e1dd591e.zip | |
x86/signal: Implement sigaltstack size validation
For historical reasons MINSIGSTKSZ is a constant which became already too
small with AVX512 support.
Add a mechanism to enforce strict checking of the sigaltstack size against
the real size of the FPU frame.
The strict check can be enabled via a config option and can also be
controlled via the kernel command line option 'strict_sas_size' independent
of the config switch.
Enabling it might break existing applications which allocate a too small
sigaltstack but 'work' because they never get a signal delivered. Though it
can be handy to filter out binaries which are not yet aware of
AT_MINSIGSTKSZ.
Also the upcoming support for dynamically enabled FPU features requires a
strict sanity check to ensure that:
- Enabling of a dynamic feature, which changes the sigframe size fits
into an enabled sigaltstack
- Installing a too small sigaltstack after a dynamic feature has been
added is not possible.
Implement the base check which is controlled by config and command line
options.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-3-chang.seok.bae@intel.com
Diffstat (limited to 'arch/x86/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d9830e7e1060..8584b30e2536 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -125,6 +125,7 @@ config X86 select CLOCKSOURCE_VALIDATE_LAST_CYCLE select CLOCKSOURCE_WATCHDOG select DCACHE_WORD_ACCESS + select DYNAMIC_SIGFRAME select EDAC_ATOMIC_SCRUB select EDAC_SUPPORT select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) @@ -2388,6 +2389,22 @@ config MODIFY_LDT_SYSCALL Saying 'N' here may make sense for embedded or server kernels. +config STRICT_SIGALTSTACK_SIZE + bool "Enforce strict size checking for sigaltstack" + depends on DYNAMIC_SIGFRAME + help + For historical reasons MINSIGSTKSZ is a constant which became + already too small with AVX512 support. Add a mechanism to + enforce strict checking of the sigaltstack size against the + real size of the FPU frame. This option enables the check + by default. It can also be controlled via the kernel command + line option 'strict_sas_size' independent of this config + switch. Enabling it might break existing applications which + allocate a too small sigaltstack but 'work' because they + never get a signal delivered. + + Say 'N' unless you want to really enforce this check. + source "kernel/livepatch/Kconfig" endmenu |