Enforce an upper limit of 100,000 bytes on commands executed via
wfShellExec() to avoid HHVM crash resulting from process spawned with
argument exceeding MAX_ARG_STRLEN, as defined in binfmts.h
Bug: T129506
Signed-off-by: Chad Horohoe <chadh@wikimedia.org>
// for future use with the api, and for use by extensions
define( 'CONTENT_FORMAT_XML', 'application/xml' );
/**@}*/
+
+/**@{
+ * Max string length for shell invocations; based on binfmts.h
+ */
+define( 'SHELL_MAX_ARG_STRLEN', '100000');
+/**@}*/
// Hide compatibility functions from Doxygen
/// @cond
-
/**
* Compatibility functions
*
}
wfDebug( "wfShellExec: $cmd\n" );
+ // Don't try to execute commands that exceed Linux's MAX_ARG_STRLEN.
+ // Other platforms may be more accomodating, but we don't want to be
+ // accomodating, because very long commands probably include user
+ // input. See T129506.
+ if ( strlen( $cmd ) > SHELL_MAX_ARG_STRLEN ) {
+ throw new Exception( __METHOD__ . '(): total length of $cmd must not exceed SHELL_MAX_ARG_STRLEN' );
+ }
+
$desc = [
0 => [ 'file', 'php://stdin', 'r' ],
1 => [ 'pipe', 'w' ],