9134b5a464
commit 2198d07c509f1db4a1185d1f65aaada794c6ea59 upstream. All occurrences of the scs_load macro load the value of the shadow call stack pointer from the task which is current at that point. So instead of taking a task struct register argument in the scs_load macro to specify the task struct to load from, let's always reference the current task directly. This should make it much harder to exploit any instruction sequences reloading the shadow call stack pointer register from memory. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230109174800.3286265-2-ardb@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
31 lines
507 B
C
31 lines
507 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_SCS_H
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#define _ASM_SCS_H
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#ifdef __ASSEMBLY__
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#include <asm/asm-offsets.h>
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#ifdef CONFIG_SHADOW_CALL_STACK
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scs_sp .req x18
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.macro scs_load_current
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get_current_task scs_sp
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ldr scs_sp, [scs_sp, #TSK_TI_SCS_SP]
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.endm
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.macro scs_save tsk, tmp
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str scs_sp, [\tsk, #TSK_TI_SCS_SP]
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.endm
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#else
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.macro scs_load_current
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.endm
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.macro scs_save tsk, tmp
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.endm
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#endif /* CONFIG_SHADOW_CALL_STACK */
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#endif /* __ASSEMBLY __ */
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#endif /* _ASM_SCS_H */
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