linux-user/aarch64: Fix SHADOW_STACK_SET_TOKEN

[PATCH for-11.1] linux-user/aarch64: Fix SHADOW_STACK_SET_TOKEN

Richard Henderson posted 1 patch 2 months ago

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Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20260729191711.71217-1-richard.henderson@linaro.org

Maintainers: Laurent Vivier <laurent@vivier.eu>, Helge Deller <deller@gmx.de>, Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>

linux-user/syscall.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

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[PATCH for-11.1] linux-user/aarch64: Fix SHADOW_STACK_SET_TOKEN

Posted by Richard Henderson 2 months ago

The token is not computed via TARGET_PAGE_SIZE, but via a fixed 12-bit field.

Cc: qemu-stable@nongnu.org
Fixes: ad1afe433fa ("linux-user/aarch64: Implement map_shadow_stack syscall")
Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4106
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/syscall.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 740142825d..097d886b06 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6906,7 +6906,8 @@ static abi_long do_map_shadow_stack(CPUArchState *env, abi_ulong addr,
                 /* Leave an extra empty frame at top-of-stack. */
                 cap_ptr -= 8;
             }
-            cap_val = (cap_ptr & TARGET_PAGE_MASK) | 1;
+            /* Note the 12 bit field is unaffected by current page size. */
+            cap_val = deposit64(cap_ptr, 0, 12, 1);
             if (put_user_u64(cap_val, cap_ptr)) {
                 /* Allocation succeeded above. */
                 g_assert_not_reached();
-- 
2.43.0

Re: [PATCH for-11.1] linux-user/aarch64: Fix SHADOW_STACK_SET_TOKEN

Posted by Pierrick Bouvier 2 months ago

On 7/29/2026 12:17 PM, Richard Henderson wrote:
> The token is not computed via TARGET_PAGE_SIZE, but via a fixed 12-bit field.
> 
> Cc: qemu-stable@nongnu.org
> Fixes: ad1afe433fa ("linux-user/aarch64: Implement map_shadow_stack syscall")
> Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4106
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  linux-user/syscall.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com>