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Fix very high stack usage in SSL debug code

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Use a switch instead of an array. The array was very hollow for some enum
types such as mbedtls_ssl_protocol_version (which formerly used small
values, but switched to using the protocol encoding as enum values in Mbed
TLS 3.2.0). Optimizing compilers know how to compile a switch into a lookup
table when the range warrants it.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2023-06-20 17:48:18 +02:00
parent 44ff5a9208
commit fd235bc9df
2 changed files with 8 additions and 11 deletions
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3
ChangeLog.d/ssl_debug_helpers-stack_usage.txt Normal file
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@ -0,0 +1,3 @@
Bugfix
* Fix very high stack usage in SSL debug code. Reported by Maximilian
Gerhardt in #7804.

14
scripts/generate_ssl_debug_helpers.py
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@ -209,24 +209,18 @@ class EnumDefinition:
continue continue
member = field.strip().split()[0] member = field.strip().split()[0]
translation_table.append( translation_table.append(
'{space}[{member}] = "{member}",'.format(member=member, '{space}case {member}:\n{space} return "{member};";'
space=' '*8) .format(member=member, space=' '*8)
) )
body = textwrap.dedent('''\ body = textwrap.dedent('''\
const char *{name}_str( {prototype} in ) const char *{name}_str( {prototype} in )
{{ {{
const char * in_to_str[]= switch (in) {{
{{
{translation_table} {translation_table}
}}; default:
if( in > ( sizeof( in_to_str )/sizeof( in_to_str[0]) - 1 ) ||
in_to_str[ in ] == NULL )
{{
return "UNKNOWN_VALUE"; return "UNKNOWN_VALUE";
}} }}
return in_to_str[ in ];
}} }}
''') ''')
body = body.format(translation_table='\n'.join(translation_table), body = body.format(translation_table='\n'.join(translation_table),