x86/loader: Rectify the address of setup_data

[PATCH] x86/loader: Rectify the address of setup_data

Xiaoyao Li posted 1 patch 3 months ago

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git fetch https://github.com/patchew-project/qemu tags/patchew/20250814141406.2371767-1-xiaoyao.li@intel.com

Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>

hw/i386/x86-common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

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[PATCH] x86/loader: Rectify the address of setup_data

Posted by Xiaoyao Li 3 months ago

Commit 214191f6b574 ("x86/loader: read complete kernel") changed the
semantics of kernel_size from the piggyback kernel to the whole kernel
file, which leads to the setup_data_offset contains setup_size and leads
to wrong address of setup_data being written in header[0x250].

Fix it by minusing setup_size.

Fixes: 214191f6b574 ("x86/loader: read complete kernel")
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 hw/i386/x86-common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c
index 7512be64d67b..127b85eb02cc 100644
--- a/hw/i386/x86-common.c
+++ b/hw/i386/x86-common.c
@@ -935,7 +935,7 @@ void x86_load_linux(X86MachineState *x86ms,
         kernel_size = setup_data_offset + sizeof(struct setup_data) + dtb_size;
         kernel = g_realloc(kernel, kernel_size);
 
-        stq_le_p(header + 0x250, prot_addr + setup_data_offset);
+        stq_le_p(header + 0x250, prot_addr + setup_data_offset - setup_size);
 
         setup_data = (struct setup_data *)(kernel + setup_data_offset);
         setup_data->next = 0;
-- 
2.43.0

Re: [PATCH] x86/loader: Rectify the address of setup_data

Posted by Xiaoyao Li 2 months ago

On 8/14/2025 10:14 PM, Xiaoyao Li wrote:
> Commit 214191f6b574 ("x86/loader: read complete kernel") changed the
> semantics of kernel_size from the piggyback kernel to the whole kernel
> file, which leads to the setup_data_offset contains setup_size and leads
> to wrong address of setup_data being written in header[0x250].
> 
> Fix it by minusing setup_size.

Gentle ping.

> Fixes: 214191f6b574 ("x86/loader: read complete kernel")
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
>   hw/i386/x86-common.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c
> index 7512be64d67b..127b85eb02cc 100644
> --- a/hw/i386/x86-common.c
> +++ b/hw/i386/x86-common.c
> @@ -935,7 +935,7 @@ void x86_load_linux(X86MachineState *x86ms,
>           kernel_size = setup_data_offset + sizeof(struct setup_data) + dtb_size;
>           kernel = g_realloc(kernel, kernel_size);
>   
> -        stq_le_p(header + 0x250, prot_addr + setup_data_offset);
> +        stq_le_p(header + 0x250, prot_addr + setup_data_offset - setup_size);
>   
>           setup_data = (struct setup_data *)(kernel + setup_data_offset);
>           setup_data->next = 0;