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curl: Fix UAF on clone due to callback data pointer mismatch #24760

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ndossche wants to merge 1 commit into from
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curl: Fix UAF on clone due to callback data pointer mismatch #24760

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10 changes: 8 additions & 2 deletions ext/curl/interface.c
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Original file line number Diff line number Diff line change
Expand Up @@ -813,6 +813,10 @@ static int curl_ssh_hostkeyfunction(void *clientp, int keytype, const char *key,
php_curl *ch = (php_curl *)clientp;
int rval = CURLKHMATCH_MISMATCH; /* cancel connection in case of an exception */

if (!ZEND_FCC_INITIALIZED(ch->handlers.sshhostkey)) {

@ndossche ndossche Oct 26, 2026

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This is adjacently related, matches other handlers, otherwise a nulled callback can crash

return rval;
}

#if PHP_CURL_DEBUG
fprintf(stderr, "curl_ssh_hostkeyfunction() called\n");
fprintf(stderr, "clientp = %x, keytype = %d, key = %s, keylen = %zu\n", clientp, keytype, key, keylen);
Expand Down Expand Up @@ -1284,8 +1288,11 @@ static void php_curl_copy_fcc_with_option(php_curl *ch, CURLoption option, zend_
{
if (ZEND_FCC_INITIALIZED(*source_fcc)) {
zend_fcc_dup(target_fcc, source_fcc);
curl_easy_setopt(ch->cp, option, (void *) ch);
}

/* The callback data (i.e. pointer to the curl handle) stays even if a user callback
* is reset to NULL. Ensure the data pointer always points to the new handle. */
curl_easy_setopt(ch->cp, option, (void *) ch);
}

void _php_setup_easy_copy_handlers(php_curl *ch, php_curl *source)
Expand Down Expand Up @@ -1325,7 +1332,6 @@ void _php_setup_easy_copy_handlers(php_curl *ch, php_curl *source)
curl_easy_setopt(ch->cp, CURLOPT_FILE, (void *) ch);
curl_easy_setopt(ch->cp, CURLOPT_INFILE, (void *) ch);
curl_easy_setopt(ch->cp, CURLOPT_WRITEHEADER, (void *) ch);
curl_easy_setopt(ch->cp, CURLOPT_DEBUGDATA, (void *) ch);

@ndossche ndossche Oct 26, 2026

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This is already done now by the php_curl_copy_fcc_with_option CURLOPT_DEBUGDATA code below


php_curl_copy_fcc_with_option(ch, CURLOPT_PROGRESSDATA, &ch->handlers.progress, &source->handlers.progress);
php_curl_copy_fcc_with_option(ch, CURLOPT_XFERINFODATA, &ch->handlers.xferinfo, &source->handlers.xferinfo);
Expand Down
27 changes: 27 additions & 0 deletions ext/curl/tests/curl_copy_handle_progress_null_uaf.phpt
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@@ -0,0 +1,27 @@
--TEST--
Cloning a curl handle whose CURLOPT_PROGRESSFUNCTION was reset to null must not reference the source handle
--EXTENSIONS--
curl
--FILE--
<?php
$srcfile = __DIR__ . '/curl_copy_handle_progress_null_uaf.txt';
file_put_contents($srcfile, "Test.");

$ch1 = curl_init();
curl_setopt($ch1, CURLOPT_URL, "file://" . $srcfile);
curl_setopt($ch1, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch1, CURLOPT_NOPROGRESS, false);
curl_setopt($ch1, CURLOPT_PROGRESSFUNCTION, fn() => 0);
curl_setopt($ch1, CURLOPT_PROGRESSFUNCTION, null);

$ch2 = clone $ch1;
unset($ch1);

var_dump(curl_exec($ch2));
?>
--CLEAN--
<?php
@unlink(__DIR__ . '/curl_copy_handle_progress_null_uaf.txt');
?>
--EXPECT--
string(5) "Test."
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