From ea8d2d19ad17ceafc883b86e448a405cf7808927 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Mon, 17 Dec 2012 16:03:20 -0800 Subject: exec: use -ELOOP for max recursion depth commit d740269867021faf4ce38a449353d2b986c34a67 upstream. To avoid an explosion of request_module calls on a chain of abusive scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon as maximum recursion depth is hit, the error will fail all the way back up the chain, aborting immediately. This also has the side-effect of stopping the user's shell from attempting to reexecute the top-level file as a shell script. As seen in the dash source: if (cmd != path_bshell && errno == ENOEXEC) { *argv-- = cmd; *argv = cmd = path_bshell; goto repeat; } The above logic was designed for running scripts automatically that lacked the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC, things continue to behave as the shell expects. Additionally, when tracking recursion, the binfmt handlers should not be involved. The recursion being tracked is the depth of calls through search_binary_handler(), so that function should be exclusively responsible for tracking the depth. Signed-off-by: Kees Cook Cc: halfdog Cc: P J P Cc: Alexander Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- include/linux/binfmts.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index 384e37f6834f..718eb0bca6fc 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -67,8 +67,6 @@ struct linux_binprm { #define BINPRM_FLAGS_EXECFD_BIT 1 #define BINPRM_FLAGS_EXECFD (1 << BINPRM_FLAGS_EXECFD_BIT) -#define BINPRM_MAX_RECURSION 4 - /* Function parameter for binfmt->coredump */ struct coredump_params { long signr; -- cgit v1.2.3