x86/pkeys: Update PKRU to enable all pkeys before XSAVE

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If the alternate signal stack is protected by a different PKEY than the
current execution stack, copying XSAVE data to the sigaltstack will fail
if its PKEY is not enabled in the PKRU register.

It's unknown which pkey was used by the application for the altstack, so
enable all PKEYS before XSAVE.

But this updated PKRU value is also pushed onto the sigframe, which
means the register value restored from sigcontext will be different from
the user-defined one, which is incorrect.

Fix that by overwriting the PKRU value on the sigframe with the original,
user-defined PKRU.

Signed-off-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240802061318.2140081-4-aruna.ramakrishna@oracle.com

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Aruna Ramakrishna 2024-08-02 06:13:16 +00:00 • committed by Thomas Gleixner

parent 84ee6e8d19

commit 70044df250

2 changed files with 19 additions and 4 deletions

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11

arch/x86/kernel/fpu/signal.c

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12

arch/x86/kernel/signal.c

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