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Fix GH-20257: heap overflow on empty message in lf mode. #20258

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Fix GH-20257: heap overflow on empty message in lf mode. #20258

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aa3afd6
Fix GH-20257: heap overflow on empty message in `lf` mode.
devnexen Oct 22, 2025
de52e44
fix test
devnexen Oct 22, 2025
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42 changes: 22 additions & 20 deletions ext/standard/mail.c
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Original file line number Diff line number Diff line change
Expand Up @@ -614,34 +614,36 @@ PHPAPI bool php_mail(const char *to, const char *subject, const char *message, c
size_t msg_len = strlen(message);
size_t new_len = 0;

for (size_t i = 0; i < msg_len - 1; ++i) {
if (message[i] == '\r' && message[i + 1] == '\n') {
++new_len;
if (msg_len > 0) {
for (size_t i = 0; i < msg_len - 1; ++i) {
if (message[i] == '\r' && message[i + 1] == '\n') {
++new_len;
}
}
}

if (new_len == 0) {
fprintf(sendmail, "%s", message);
} else {
converted_message = emalloc(msg_len - new_len + 1);
size_t j = 0;
for (size_t i = 0; i < msg_len; ++i) {
if (i < msg_len - 1 && message[i] == '\r' && message[i + 1] == '\n') {
converted_message[j++] = '\n';
++i; /* skip LF part */
} else {
converted_message[j++] = message[i];
if (new_len == 0) {
fprintf(sendmail, "%s", message);
} else {
converted_message = emalloc(msg_len - new_len + 1);
size_t j = 0;
for (size_t i = 0; i < msg_len; ++i) {
if (i < msg_len - 1 && message[i] == '\r' && message[i + 1] == '\n') {
converted_message[j++] = '\n';
++i; /* skip LF part */
} else {
converted_message[j++] = message[i];
}
}
}

converted_message[j] = '\0';
fprintf(sendmail, "%s", converted_message);
efree(converted_message);
converted_message[j] = '\0';
fprintf(sendmail, "%s", converted_message);
efree(converted_message);
}
}
} else {
fprintf(sendmail, "%s", message);
}

fprintf(sendmail, "%s", line_sep);
#ifdef PHP_WIN32
ret = pclose(sendmail);
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17 changes: 17 additions & 0 deletions ext/standard/tests/mail/gh20257.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
--TEST--
GH-20257: heap overflow with empty message and mail.cr_lf_mode=lf set
--INI--
sendmail_path="exit 1"
mail.cr_lf_mode=lf
--CREDITS--
YuanchengJiang
--FILE--
<?php
$to = "user@example.com";
$subject = $message = "";
var_dump(mail($to, $subject, $message));
?>
--EXPECTF--

Warning: mail(): Sendmail exited with non-zero exit code 1 in %s on line %d
bool(false)