From 440b7f8653e4ed8f6e1425145208050b795e9a6c Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Thu, 31 Oct 2019 18:25:39 +0100 Subject: Avoid late failure in dlopen in global scope update [BZ #25112] The call to add_to_global in dl_open_worker happens after running ELF constructors for new objects. At this point, proper recovery from malloc failure would be quite complicated: We would have to run the ELF destructors and close all opened objects, something that we currently do not do. Instead, this change splits add_to_global into two phases, add_to_global_resize (which can raise an exception, called before ELF constructors run), and add_to_global_update (which cannot, called after ELF constructors). A complication arises due to recursive dlopen: After the inner dlopen consumes some space, the pre-allocation in the outer dlopen may no longer be sufficient. A new member in the namespace structure, _ns_global_scope_pending_adds keeps track of the maximum number of objects that need to be added to the global scope. This enables the inner add_to_global_resize call to take into account the needs of an outer dlopen. Most code in the dynamic linker assumes that the number of global scope entries fits into an unsigned int (matching the r_nlist member of struct r_scop_elem). Therefore, change the type of _ns_global_scope_alloc to unsigned int (from size_t), and add overflow checks. Change-Id: Ie08e2f318510d5a6a4bcb1c315f46791b5b77524 --- sysdeps/generic/ldsodefs.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'sysdeps/generic') diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 9737780136..c0017b8a6d 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -328,7 +328,14 @@ struct rtld_global /* This is zero at program start to signal that the global scope map is allocated by rtld. Later it keeps the size of the map. It might be reset if in _dl_close if the last global object is removed. */ - size_t _ns_global_scope_alloc; + unsigned int _ns_global_scope_alloc; + + /* During dlopen, this is the number of objects that still need to + be added to the global scope map. It has to be taken into + account when resizing the map, for future map additions after + recursive dlopen calls from ELF constructors. */ + unsigned int _ns_global_scope_pending_adds; + /* Search table for unique objects. */ struct unique_sym_table { -- cgit 1.4.1