* [Qemu-devel] [PATCH] smbios: catch zero-length strings
@ 2014-01-21 12:24 Gerd Hoffmann
2014-01-21 13:26 ` [Qemu-devel] [SeaBIOS] " Markus Armbruster
2014-01-21 19:52 ` Kevin O'Connor
0 siblings, 2 replies; 4+ messages in thread
From: Gerd Hoffmann @ 2014-01-21 12:24 UTC (permalink / raw)
To: seabios; +Cc: armbru, qemu-devel, Gerd Hoffmann
qemu may pass us zero-length strings for smbios fields, when starting
qemu this way ...
qemu -smbios type=1,version=,serial=test
... for example.
Today we don't specifically handle them and simply append them to the
string list. Therefore we get two string-terminating zeros in a row.
Result is that we by accident create a end-of-entry marker in the middle
of the entry.
Fix this by handling zero-length strings like non-present strings.
Cc: armbru@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
src/fw/smbios.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/src/fw/smbios.c b/src/fw/smbios.c
index affb9be..d549329 100644
--- a/src/fw/smbios.c
+++ b/src/fw/smbios.c
@@ -133,20 +133,24 @@ get_external(int type, char **p, unsigned *nr_structs,
do { \
size = get_field(type, offsetof(struct smbios_type_##type, \
field), end); \
- if (size > 0) { \
+ if (size == 1) { \
+ /* zero-length string, skip to avoid bogous end marker */ \
+ p->field = 0; \
+ } else if (size > 1) { \
end += size; \
+ p->field = ++str_index; \
} else { \
memcpy(end, def, sizeof(def)); \
end += sizeof(def); \
+ p->field = ++str_index; \
} \
- p->field = ++str_index; \
} while (0)
#define load_str_field_or_skip(type, field) \
do { \
size = get_field(type, offsetof(struct smbios_type_##type, \
field), end); \
- if (size > 0) { \
+ if (size > 1) { \
end += size; \
p->field = ++str_index; \
} else { \
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [SeaBIOS] [PATCH] smbios: catch zero-length strings
2014-01-21 12:24 [Qemu-devel] [PATCH] smbios: catch zero-length strings Gerd Hoffmann
@ 2014-01-21 13:26 ` Markus Armbruster
2014-01-22 7:58 ` Gerd Hoffmann
2014-01-21 19:52 ` Kevin O'Connor
1 sibling, 1 reply; 4+ messages in thread
From: Markus Armbruster @ 2014-01-21 13:26 UTC (permalink / raw)
To: Gerd Hoffmann; +Cc: seabios, qemu-devel
Gerd Hoffmann <kraxel@redhat.com> writes:
> qemu may pass us zero-length strings for smbios fields, when starting
> qemu this way ...
>
> qemu -smbios type=1,version=,serial=test
>
> ... for example.
>
> Today we don't specifically handle them and simply append them to the
> string list. Therefore we get two string-terminating zeros in a row.
> Result is that we by accident create a end-of-entry marker in the middle
> of the entry.
And dmidecode screaming bloody murder :) More detail than you probably
want to know at https://bugzilla.redhat.com/show_bug.cgi?id=1052837
> Fix this by handling zero-length strings like non-present strings.
>
> Cc: armbru@redhat.com
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Spelling correction inline.
Reviewed-by: Markus Armbruster <armbru@redhat.com>
> ---
> src/fw/smbios.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/src/fw/smbios.c b/src/fw/smbios.c
> index affb9be..d549329 100644
> --- a/src/fw/smbios.c
> +++ b/src/fw/smbios.c
> @@ -133,20 +133,24 @@ get_external(int type, char **p, unsigned *nr_structs,
> do { \
> size = get_field(type, offsetof(struct smbios_type_##type, \
> field), end); \
> - if (size > 0) { \
> + if (size == 1) { \
> + /* zero-length string, skip to avoid bogous end marker */ \
s/bogous/bogus/
> + p->field = 0; \
> + } else if (size > 1) { \
> end += size; \
> + p->field = ++str_index; \
> } else { \
> memcpy(end, def, sizeof(def)); \
> end += sizeof(def); \
> + p->field = ++str_index; \
> } \
> - p->field = ++str_index; \
> } while (0)
>
> #define load_str_field_or_skip(type, field) \
> do { \
> size = get_field(type, offsetof(struct smbios_type_##type, \
> field), end); \
> - if (size > 0) { \
> + if (size > 1) { \
> end += size; \
> p->field = ++str_index; \
> } else { \
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [SeaBIOS] [PATCH] smbios: catch zero-length strings
2014-01-21 12:24 [Qemu-devel] [PATCH] smbios: catch zero-length strings Gerd Hoffmann
2014-01-21 13:26 ` [Qemu-devel] [SeaBIOS] " Markus Armbruster
@ 2014-01-21 19:52 ` Kevin O'Connor
1 sibling, 0 replies; 4+ messages in thread
From: Kevin O'Connor @ 2014-01-21 19:52 UTC (permalink / raw)
To: Gerd Hoffmann; +Cc: seabios, armbru, qemu-devel
On Tue, Jan 21, 2014 at 01:24:02PM +0100, Gerd Hoffmann wrote:
> qemu may pass us zero-length strings for smbios fields, when starting
> qemu this way ...
>
> qemu -smbios type=1,version=,serial=test
>
> ... for example.
>
> Today we don't specifically handle them and simply append them to the
> string list. Therefore we get two string-terminating zeros in a row.
> Result is that we by accident create a end-of-entry marker in the middle
> of the entry.
>
> Fix this by handling zero-length strings like non-present strings.
Looks okay to me.
I wish we could get all of the smbios stuff moved to qemu.
-Kevin
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-01-22 7:58 UTC | newest]
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2014-01-21 12:24 [Qemu-devel] [PATCH] smbios: catch zero-length strings Gerd Hoffmann
2014-01-21 13:26 ` [Qemu-devel] [SeaBIOS] " Markus Armbruster
2014-01-22 7:58 ` Gerd Hoffmann
2014-01-21 19:52 ` Kevin O'Connor
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