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authorThomas Gleixner <tglx@linutronix.de>2021-10-22 01:55:06 +0300
committerBorislav Petkov <bp@suse.de>2021-10-26 11:18:09 +0300
commit3aac3ebea08f2d342364f827c8979ab0e1dd591e (patch)
tree66cfbec408ebb30544063cde4b49094da02c6d66 /Documentation/admin-guide
parent1bdda24c4af64cd2d65dec5192ab624c5fee7ca0 (diff)
downloadlinux-3aac3ebea08f2d342364f827c8979ab0e1dd591e.tar.xz
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 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt9
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 43dc35fe5bc0..eb9a73ad91a0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5497,6 +5497,15 @@
stifb= [HW]
Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
+ strict_sas_size=
+ [X86]
+ Format: <bool>
+ Enable or disable strict sigaltstack size checks
+ against the required signal frame size which
+ depends on the supported FPU features. This can
+ be used to filter out binaries which have
+ not yet been made aware of AT_MINSIGSTKSZ.
+
sunrpc.min_resvport=
sunrpc.max_resvport=
[NFS,SUNRPC]