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Disallow producing NULL character with escape sequences 

NULL usually terminates the strings; allowing to produce it via escape
sequences may lead to undefined behaviour.

- Make NULL escape sequences (e.g. `\0` and `\x0`) invalid.
- Add corresponding test.
- Introduce the new message: XKB_WARNING_INVALID_ESCAPE_SEQUENCE.
master
Pierre Le Marre 2023-09-26 17:05:05 +02:00 committed by Wismill
parent a17701327e
commit ca7aa69cc0
10 changed files with 74 additions and 6 deletions
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12
doc/message-registry.md
View File

@ -6,7 +6,7 @@ NOTE: This file has been generated automatically by “update-message-registry.p
-->
This page lists the warnings and errors generated by xkbcommon.
There are currently 52 entries.
There are currently 53 entries.
@todo The documentation of the log messages is a work in progress.
@ -24,6 +24,7 @@ There are currently 52 entries.
| [XKB-150] | `wrong-statement-type` | The type of the statement is not allowed in the context | Error |
| [XKB-172] | `unsupported-geometry-section` | Geometry sections are not supported | Warning |
| [XKB-183] | `cannot-infer-key-type` | Warn if no key type can be inferred | Warning |
| [XKB-193] | `invalid-escape-sequence` | Invalid escape sequence in a string | Warning |
| [XKB-195] | `illegal-key-type-preserve-result` | The result of a key type “preserve” entry must be a subset of its input modifiers. | Warning |
| [XKB-203] | `invalid-include-statement` | Syntax error in the include statement | Error |
| [XKB-206] | `invalid-modmap-entry` | A modmap entry is invalid | Error |
@ -198,6 +199,14 @@ key <AB08> {[ comma, semicolon, periodcentered, multiply ]};
<dt>Summary</dt><dd>Warn if no key type can be inferred</dd>
</dl>
### XKB-193 – Invalid escape sequence {#XKB-193}
<dl>
<dt>Since</dt><dd>1.0.0</dd>
<dt>Type</dt><dd>Warning</dd>
<dt>Summary</dt><dd>Invalid escape sequence in a string</dd>
</dl>
### XKB-195 – Illegal key type preserve result {#XKB-195}
<dl>
@ -624,6 +633,7 @@ The modifiers used in `map` or `preserve` entries should be declared using the e
[XKB-150]: @ref XKB-150
[XKB-172]: @ref XKB-172
[XKB-183]: @ref XKB-183
[XKB-193]: @ref XKB-193
[XKB-195]: @ref XKB-195
[XKB-203]: @ref XKB-203
[XKB-206]: @ref XKB-206

5
doc/message-registry.yaml
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@ -100,6 +100,11 @@
added: ALWAYS
type: warning
description: "Warn if no key type can be inferred"
- id: "invalid-escape-sequence"
code: 193
added: ALWAYS
type: warning
description: "Invalid escape sequence in a string"
- id: "illegal-key-type-preserve-result"
code: 195
added: ALWAYS

19
src/compose/parser.c
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@ -178,13 +178,24 @@ skip_more_whitespace_and_comments:
scanner_buf_append(s, '"');
}
else if (scanner_chr(s, 'x') || scanner_chr(s, 'X')) {
if (scanner_hex(s, &o))
if (scanner_hex(s, &o) && is_valid_char((char) o)) {
scanner_buf_append(s, (char) o);
else
scanner_warn(s, "illegal hexadecimal escape sequence in string literal");
} else {
// [TODO] actually show the sequence
scanner_warn_with_code(s,
XKB_WARNING_INVALID_ESCAPE_SEQUENCE,
"illegal hexadecimal escape sequence in string literal");
}
}
else if (scanner_oct(s, &o)) {
scanner_buf_append(s, (char) o);
if (is_valid_char((char) o)) {
scanner_buf_append(s, (char) o);
} else {
// [TODO] actually show the sequence
scanner_warn_with_code(s,
XKB_WARNING_INVALID_ESCAPE_SEQUENCE,
"illegal octal escape sequence in string literal");
}
}
else {
scanner_warn(s, "unknown escape sequence (%c) in string literal", scanner_peek(s));

2
src/messages-codes.h
View File

@ -36,6 +36,8 @@ enum xkb_message_code {
XKB_WARNING_UNSUPPORTED_GEOMETRY_SECTION = 172,
/** Warn if no key type can be inferred */
XKB_WARNING_CANNOT_INFER_KEY_TYPE = 183,
/** Invalid escape sequence in a string */
XKB_WARNING_INVALID_ESCAPE_SEQUENCE = 193,
/** The result of a key type “preserve” entry must be a subset of its input modifiers. */
XKB_WARNING_ILLEGAL_KEY_TYPE_PRESERVE_RESULT = 195,
/** Syntax error in the include statement */

9
src/utils.h
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@ -65,6 +65,15 @@
#define STRINGIFY(x) #x
#define STRINGIFY2(x) STRINGIFY(x)
/* Check if a character is valid in a string literal */
static inline bool
is_valid_char(char c)
{
/* Currently we only check for NULL character, but this could be extended
* in the future to further ASCII control characters. */
return c != 0;
}
char
to_lower(char c);

10
src/xkbcomp/scanner.c
View File

@ -98,7 +98,15 @@ skip_more_whitespace_and_comments:
else if (scanner_chr(s, 'f')) scanner_buf_append(s, '\f');
else if (scanner_chr(s, 'v')) scanner_buf_append(s, '\v');
else if (scanner_chr(s, 'e')) scanner_buf_append(s, '\033');
else if (scanner_oct(s, &o)) scanner_buf_append(s, (char) o);
else if (scanner_oct(s, &o)) {
if (is_valid_char((char) o)) {
scanner_buf_append(s, (char) o);
} else {
scanner_warn_with_code(s,
XKB_WARNING_INVALID_ESCAPE_SEQUENCE,
"invalid octal escape sequence: \\%o", o);
}
}
else {
// TODO: display actual sequence! See: scanner_peek(s).
// require escaping any potential control character

12
test/compose.c
View File

@ -684,6 +684,17 @@ test_traverse(struct xkb_context *ctx)
xkb_compose_table_unref(table);
}
static void
test_escape_sequences(struct xkb_context *ctx)
{
const char *table_string = "<o> <e> : \"f\\x0o\\0o\" X\n";
assert(test_compose_seq_buffer(ctx, table_string,
XKB_KEY_o, XKB_COMPOSE_FEED_ACCEPTED, XKB_COMPOSE_COMPOSING, "", XKB_KEY_NoSymbol,
XKB_KEY_e, XKB_COMPOSE_FEED_ACCEPTED, XKB_COMPOSE_COMPOSED, "foo", XKB_KEY_X,
XKB_KEY_NoSymbol));
}
int
main(int argc, char *argv[])
{
@ -717,6 +728,7 @@ main(int argc, char *argv[])
test_include(ctx);
test_override(ctx);
test_traverse(ctx);
test_escape_sequences(ctx);
xkb_context_unref(ctx);
return 0;

9
test/data/keymaps/invalid-escape-sequence.xkb Normal file
View File

@ -0,0 +1,9 @@
xkb_keymap {
// The following include statement has an octal escape sequence that
// must be ignored. Else it would insert a NULL character and thus
// truncates the string to "evde", while we expect "evdev+aliases(qwerty)".
xkb_keycodes { include "evde\0v+aliases(qwerty)" };
xkb_types { include "complete" };
xkb_compat { include "complete" };
xkb_symbols { include "pc+us" };
};

1
test/filecomp.c
View File

@ -48,6 +48,7 @@ main(void)
assert(test_file(ctx, "keymaps/quartz.xkb"));
assert(test_file(ctx, "keymaps/no-aliases.xkb"));
assert(test_file(ctx, "keymaps/modmap-none.xkb"));
assert(test_file(ctx, "keymaps/invalid-escape-sequence.xkb"));
assert(!test_file(ctx, "keymaps/divide-by-zero.xkb"));
assert(!test_file(ctx, "keymaps/bad.xkb"));

1
tools/messages.c
View File

@ -48,6 +48,7 @@ static const struct xkb_message_entry xkb_messages[] = {
{XKB_ERROR_WRONG_STATEMENT_TYPE, "Wrong statement type"},
{XKB_WARNING_UNSUPPORTED_GEOMETRY_SECTION, "Unsupported geometry section"},
{XKB_WARNING_CANNOT_INFER_KEY_TYPE, "Cannot infer key type"},
{XKB_WARNING_INVALID_ESCAPE_SEQUENCE, "Invalid escape sequence"},
{XKB_WARNING_ILLEGAL_KEY_TYPE_PRESERVE_RESULT, "Illegal key type preserve result"},
{XKB_ERROR_INVALID_INCLUDE_STATEMENT, "Invalid include statement"},
{XKB_ERROR_INVALID_MODMAP_ENTRY, "Invalid modmap entry"},