[PATCH 0/2] arm64: signal: Fix ZT restore without ZA and clean up bounds check

[Bradley Morgan <bradley.morgan@linux.dev>]

This series addresses two separate issues in the arm64 signal frame
parsing and restoration code:

Patch 1 fixes a bug where ZT state could be restored without ZA state.
If user.za was omitted from the signal frame, restore_za_context() was
never invoked. When a signal handler touched SME before calling
rt_sigreturn(), thread_za_enabled(&current->thread) evaluated to true,
causing restore_zt_context() to overwrite ZT without restoring ZA.
We now mandate that user->za is present before restoring ZT context.

Patch 2 drops a duplicate limit - offset < size bounds check in
parse_user_sigframe() that was left over after the switch block from the
2017 frame layout rework.

Bradley Morgan (2):
  arm64/fpsimd: signal: Require ZA context when restoring ZT context
  arm64: signal: drop redundant bounds check in parse_user_sigframe()

 arch/arm64/kernel/signal.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

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2.53.0