From: Laszlo Ersek <lersek@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
Igor Mammedov <imammedo@redhat.com>
Cc: ghammer@redhat.com, lcapitulino@redhat.com,
Xiao Guangrong <guangrong.xiao@linux.intel.com>,
ehabkost@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v19 3/9] pc: add a Virtual Machine Generation ID device
Date: Wed, 10 Feb 2016 11:00:22 +0100 [thread overview]
Message-ID: <56BB0A36.7010304@redhat.com> (raw)
In-Reply-To: <20160210110920-mutt-send-email-mst@redhat.com>
On 02/10/16 10:28, Michael S. Tsirkin wrote:
> On Wed, Feb 10, 2016 at 10:51:47AM +0200, Michael S. Tsirkin wrote:
>> So maybe we should
>> leave this alone, wait until we see an actual user - this way we can
>> figure out the implementation constraints better.
>
> What I'm definitely interested in seeing is improving the
> bios_linker_loader API within QEMU.
>
> Is the below going in the right direction, in your opinion?
>
>
> diff --git a/include/hw/acpi/bios-linker-loader.h b/include/hw/acpi/bios-linker-loader.h
> index 498c0af..78d9a16 100644
> --- a/include/hw/acpi/bios-linker-loader.h
> +++ b/include/hw/acpi/bios-linker-loader.h
> @@ -17,6 +17,17 @@ void bios_linker_loader_add_checksum(GArray *linker, const char *file,
> void *start, unsigned size,
> uint8_t *checksum);
>
> +/*
> + * bios_linker_loader_add_pointer: ask guest to append address of source file
> + * into destination file at the specified pointer.
> + *
> + * @linker: linker file array
> + * @dest_file: destination file that must be changed
> + * @src_file: source file whos address must be taken
> + * @table: destination file array
> + * @pointer: location of the pointer to be patched within destination file
> + * @pointer_size: size of pointer to be patched, in bytes
> + */
> void bios_linker_loader_add_pointer(GArray *linker,
> const char *dest_file,
> const char *src_file,
> diff --git a/hw/acpi/bios-linker-loader.c b/hw/acpi/bios-linker-loader.c
> index e04d60a..84be25a 100644
> --- a/hw/acpi/bios-linker-loader.c
> +++ b/hw/acpi/bios-linker-loader.c
> @@ -142,7 +142,13 @@ void bios_linker_loader_add_pointer(GArray *linker,
> uint8_t pointer_size)
> {
> BiosLinkerLoaderEntry entry;
> - size_t offset = (gchar *)pointer - table->data;
> + size_t offset;
> +
> + assert((gchar *)pointer >= table->data);
> +
> + offset = (gchar *)pointer - table->data;
> +
> + assert(offset + pointer_size < table->len);
>
> memset(&entry, 0, sizeof entry);
> strncpy(entry.pointer.dest_file, dest_file,
>
I have two suggestions (independently of Igor's upcoming opinion):
(1) I propose to do all this arithmetic in uintptr_t, not (char*).
(2) In the last assertion, < should be <=. Both sides are exclusive, so
equality is valid.
(BTW the OVMF implementation of the linker-loader client is chock full
of verifications like the above, done in UINT64, so I can only agree
with the above safety measures, independently of vmgenid.)
Thanks
Laszlo
next prev parent reply other threads:[~2016-02-10 10:00 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 10:54 [Qemu-devel] [PATCH v19 0/9] Virtual Machine Generation ID Igor Mammedov
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 1/9] acpi: extend ACPI interface to provide access to ACPI registers and SCI irq Igor Mammedov
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 2/9] docs: vm generation id device's description Igor Mammedov
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 3/9] pc: add a Virtual Machine Generation ID device Igor Mammedov
2016-01-28 11:13 ` Michael S. Tsirkin
2016-01-28 12:03 ` Igor Mammedov
2016-01-28 12:59 ` Michael S. Tsirkin
2016-01-29 11:13 ` Igor Mammedov
2016-01-31 16:22 ` Michael S. Tsirkin
2016-02-02 9:59 ` Igor Mammedov
2016-02-02 11:16 ` Michael S. Tsirkin
2016-02-09 10:46 ` Igor Mammedov
2016-02-09 12:17 ` Michael S. Tsirkin
2016-02-11 15:16 ` Igor Mammedov
2016-02-11 16:30 ` Michael S. Tsirkin
2016-02-11 17:34 ` Marcel Apfelbaum
2016-02-12 6:15 ` Michael S. Tsirkin
2016-02-15 10:30 ` Igor Mammedov
2016-02-15 11:26 ` Michael S. Tsirkin
2016-02-15 13:56 ` Igor Mammedov
2016-02-16 10:05 ` Marcel Apfelbaum
2016-02-16 12:17 ` Igor Mammedov
2016-02-16 12:36 ` Marcel Apfelbaum
2016-02-16 13:51 ` Igor Mammedov
2016-02-16 14:53 ` Michael S. Tsirkin
2016-02-16 15:10 ` Michael S. Tsirkin
2016-02-10 8:51 ` Michael S. Tsirkin
2016-02-10 9:28 ` Michael S. Tsirkin
2016-02-10 10:00 ` Laszlo Ersek [this message]
2016-01-28 13:48 ` Laszlo Ersek
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 4/9] tests: add a unit test for the vmgenid device Igor Mammedov
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 5/9] qmp/hmp: add query-vm-generation-id and 'info vm-generation-id' commands Igor Mammedov
2016-02-09 17:31 ` Eric Blake
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 6/9] qmp/hmp: add set-vm-generation-id commands Igor Mammedov
2016-02-09 17:33 ` Eric Blake
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 8/9] pc: put PIIX3 in slot 1 explicitly and cleanup functions assignment Igor Mammedov
2016-01-28 10:54 ` [Qemu-devel] [PATCH v19 9/9] pc/q53: by default put vmgenid device as an function of ISA bridge Igor Mammedov
2016-01-28 10:58 ` [Qemu-devel] [PATCH v19 7/9] machine: add properties to compat_props incrementaly Igor Mammedov
2016-01-28 14:02 ` Eduardo Habkost
2016-01-28 17:00 ` Igor Mammedov
2016-02-03 17:55 ` [Qemu-devel] qdev & hw/core owner? (was Re: [PATCH v19 7/9] machine: add properties to compat_props incrementaly) Eduardo Habkost
2016-02-03 18:46 ` Laszlo Ersek
2016-02-03 19:06 ` Michael S. Tsirkin
2016-02-04 11:31 ` Paolo Bonzini
2016-02-04 11:41 ` Andreas Färber
2016-02-04 11:55 ` Paolo Bonzini
2016-02-04 12:06 ` Michael S. Tsirkin
2016-02-05 7:49 ` Markus Armbruster
2016-02-05 7:51 ` Marcel Apfelbaum
2016-02-11 19:41 ` Eduardo Habkost
2016-02-12 9:17 ` Marcel Apfelbaum
2016-02-12 11:22 ` Andreas Färber
2016-02-12 18:17 ` Eduardo Habkost
2016-02-12 22:30 ` Paolo Bonzini
2016-02-12 18:09 ` Eduardo Habkost
2016-02-05 7:52 ` Markus Armbruster
2016-02-04 12:03 ` Michael S. Tsirkin
2016-02-04 12:12 ` Marcel Apfelbaum
2016-01-29 12:51 ` [Qemu-devel] [PATCH v19 7/9] machine: add properties to compat_props incrementaly Cornelia Huck
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