[PATCH v2] smbios: Fix table when no string is present
From: Matthias Brugger mbrugger@suse.com
When no string is present in a table, next_ptr points to the same location as eos. When calculating the string table length, we would only reserve one \0. By spec a SMBIOS table has to end with two \0\0 when no strings a present.
Signed-off-by: Matthias Brugger mbrugger@suse.com
---
Changes in v2: - check in smbios_string_table_len if no string present and return value accordingly
lib/smbios.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/lib/smbios.c b/lib/smbios.c index 9eb226ec9f..fd57d8694f 100644 --- a/lib/smbios.c +++ b/lib/smbios.c @@ -191,6 +191,10 @@ int smbios_update_version(const char *version) */ static int smbios_string_table_len(const struct smbios_ctx *ctx) { + /* In case no string is defined we have to return two \0 */ + if (ctx->next_ptr == ctx->eos) + return 2; + /* Allow for the final \0 after all strings */ return (ctx->next_ptr + 1) - ctx->eos; }
Hi Matthias,
On Tue, 6 Apr 2021 at 21:04, matthias.bgg@kernel.org wrote:
From: Matthias Brugger mbrugger@suse.com
When no string is present in a table, next_ptr points to the same location as eos. When calculating the string table length, we would only reserve one \0. By spec a SMBIOS table has to end with two \0\0 when no strings a present.
Signed-off-by: Matthias Brugger mbrugger@suse.com
Changes in v2:
- check in smbios_string_table_len if no string present and return value accordingly
This looks like a better idea to me. But where are the \0 bytes actually written? Perhaps that should be in smbios_set_eos()?
lib/smbios.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/lib/smbios.c b/lib/smbios.c index 9eb226ec9f..fd57d8694f 100644 --- a/lib/smbios.c +++ b/lib/smbios.c @@ -191,6 +191,10 @@ int smbios_update_version(const char *version) */ static int smbios_string_table_len(const struct smbios_ctx *ctx) {
/* In case no string is defined we have to return two \0 */if (ctx->next_ptr == ctx->eos)return 2;/* Allow for the final \0 after all strings */ return (ctx->next_ptr + 1) - ctx->eos;}
2.30.2
Regards, Simon
On 4/7/21 18:14, Simon Glass wrote:
Hi Matthias,
On Tue, 6 Apr 2021 at 21:04, matthias.bgg@kernel.org wrote:
From: Matthias Brugger mbrugger@suse.com
When no string is present in a table, next_ptr points to the same location as eos. When calculating the string table length, we would only reserve one \0. By spec a SMBIOS table has to end with two \0\0 when no strings a present.
Signed-off-by: Matthias Brugger mbrugger@suse.com
Changes in v2:
- check in smbios_string_table_len if no string present and return value accordingly
This looks like a better idea to me. But where are the \0 bytes actually written? Perhaps that should be in smbios_set_eos()?
We have defined SMBIOS_STRUCT_EOS_BYTES as 2 and we have an array char eos[SMBIOS_STRUCT_EOS_BYTES]; at the end of each SMBIOS structure.
We call memset(t, 0, sizeof(struct smbios_typeX)); for each table. This is enough to ensure two zero bytes exist if there are no strings.
Reviewed-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com
lib/smbios.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/lib/smbios.c b/lib/smbios.c index 9eb226ec9f..fd57d8694f 100644 --- a/lib/smbios.c +++ b/lib/smbios.c @@ -191,6 +191,10 @@ int smbios_update_version(const char *version) */ static int smbios_string_table_len(const struct smbios_ctx *ctx) {
/* In case no string is defined we have to return two \0 */if (ctx->next_ptr == ctx->eos)return 2;/* Allow for the final \0 after all strings */ return (ctx->next_ptr + 1) - ctx->eos;-- 2.30.2
Regards, Simon
participants (3)
-
Heinrich Schuchardt -
matthias.bgg＠kernel.org -
Simon Glass