[PATCH] dump/win_dump: limit number of processed PRCBs

[PATCH] dump/win_dump: limit number of processed PRCBs

[Viktor Prutyanov]

When number of CPUs utilized by guest Windows is less than defined in
QEMU (i.e., desktop versions of Windows severely limits number of CPU
sockets), patch_and_save_context routine accesses non-existent PRCB and
fails. So, limit number of processed PRCBs by NumberProcessors taken
from guest Windows driver.

Signed-off-by: Viktor Prutyanov <viktor.prutyanov@redhat.com>
---
 dump/win_dump.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/dump/win_dump.c b/dump/win_dump.c
index fd91350fbb..f20b6051b6 100644
--- a/dump/win_dump.c
+++ b/dump/win_dump.c
@@ -273,6 +273,13 @@ static void patch_and_save_context(WinDumpHeader *h, bool x64,
         uint64_t Context;
         WinContext ctx;
 
+        if (i >= WIN_DUMP_FIELD(NumberProcessors)) {
+            warn_report("win-dump: number of QEMU CPUs is bigger than"
+                        " NumberProcessors (%u) in guest Windows",
+                        WIN_DUMP_FIELD(NumberProcessors));
+            return;
+        }
+
         if (cpu_read_ptr(x64, first_cpu,
                 KiProcessorBlock + i * win_dump_ptr_size(x64),
                 &Prcb)) {
-- 
2.35.1

Re: [PATCH] dump/win_dump: limit number of processed PRCBs

[Marc-André Lureau]

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Hi

On Thu, Oct 20, 2022 at 3:59 AM Viktor Prutyanov <
viktor.prutyanov@redhat.com> wrote:

> When number of CPUs utilized by guest Windows is less than defined in
> QEMU (i.e., desktop versions of Windows severely limits number of CPU
> sockets), patch_and_save_context routine accesses non-existent PRCB and
> fails. So, limit number of processed PRCBs by NumberProcessors taken
> from guest Windows driver.
>
> Signed-off-by: Viktor Prutyanov <viktor.prutyanov@redhat.com>
>

Assuming the used CPUs are in the same order. Or is there a way to query it
instead?

lgtm otherwise
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



> ---
>  dump/win_dump.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/dump/win_dump.c b/dump/win_dump.c
> index fd91350fbb..f20b6051b6 100644
> --- a/dump/win_dump.c
> +++ b/dump/win_dump.c
> @@ -273,6 +273,13 @@ static void patch_and_save_context(WinDumpHeader *h,
> bool x64,
>          uint64_t Context;
>          WinContext ctx;
>
> +        if (i >= WIN_DUMP_FIELD(NumberProcessors)) {
> +            warn_report("win-dump: number of QEMU CPUs is bigger than"
> +                        " NumberProcessors (%u) in guest Windows",
> +                        WIN_DUMP_FIELD(NumberProcessors));
> +            return;
> +        }
> +
>          if (cpu_read_ptr(x64, first_cpu,
>                  KiProcessorBlock + i * win_dump_ptr_size(x64),
>                  &Prcb)) {
> --
> 2.35.1
>
>

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