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Fix GH-16812: UAF on readline_info() after readline_write_history() c… #16813

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Fix GH-16812: UAF on readline_info() after readline_write_history() c… #16813

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f16a9c7
Fix GH-16812: UAF on readline_info() after readline_write_history() c…
devnexen Nov 15, 2024
df81263
add test
devnexen Nov 15, 2024
1db70c0
changes from feedback, copying original before hand instead.
devnexen Nov 15, 2024
4650692
enable the test on windows
devnexen Nov 15, 2024
ca32a24
enable for the old readline lib too
devnexen Nov 15, 2024
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6 changes: 4 additions & 2 deletions ext/readline/readline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,7 @@ PHP_FUNCTION(readline_info)
add_assoc_long(return_value,"attempted_completion_over",rl_attempted_completion_over);
} else {
if (zend_string_equals_literal_ci(what,"line_buffer")) {
oldstr = rl_line_buffer;
oldstr = strdup(rl_line_buffer ? rl_line_buffer : "");
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The strdup("") doesn't seem to be necessary (that's already handled by SAFE_STRING(). It's not wrong though, and performance is likely irrelevant here.

if (value) {
if (!try_convert_to_string(value)) {
RETURN_THROWS();
Expand All @@ -191,7 +191,8 @@ PHP_FUNCTION(readline_info)
rl_line_buffer = malloc(Z_STRLEN_P(value) + 1);
} else if (strlen(oldstr) < Z_STRLEN_P(value)) {
rl_extend_line_buffer(Z_STRLEN_P(value) + 1);
oldstr = rl_line_buffer;
free(oldstr);
oldstr = strdup(rl_line_buffer ? rl_line_buffer : "");
Comment on lines +194 to +195
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Since we touch this code path (libreadline only), we should also run the test against libreadline.

}
memcpy(rl_line_buffer, Z_STRVAL_P(value), Z_STRLEN_P(value) + 1);
#else
Expand All @@ -208,6 +209,7 @@ PHP_FUNCTION(readline_info)
#endif
}
RETVAL_STRING(SAFE_STRING(oldstr));
free(oldstr);
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Ah, right, good idea!

} else if (zend_string_equals_literal_ci(what, "point")) {
RETVAL_LONG(rl_point);
#ifndef PHP_WIN32
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15 changes: 15 additions & 0 deletions ext/readline/tests/gh16812.phpt
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@@ -0,0 +1,15 @@
--TEST--
GH-16812 readline_info(): UAF
--EXTENSIONS--
readline
--SKIPIF--
<?php
if (getenv('SKIP_REPEAT')) die("skip readline has global state");
?>
--FILE--
<?php
readline_write_history(NULL);
var_dump(readline_info('line_buffer', 'test'));
?>
--EXPECT--
string(0) ""