intern_cu (and __libdwfl_nextcu) didn't correctly handle immediately seeing the CU EOF marker. In that case the *nextp pointer (first_cu) returned by intern_cu is -1. And less_layzy will immediately destroy the found CU node. So don't use the *found result after calling less_lazy.
Found by afl-fuzz. Signed-off-by: Mark Wielaard <[email protected]> --- libdwfl/ChangeLog | 6 ++++++ libdwfl/cu.c | 8 +++++--- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog index 6b51880..de785dc 100644 --- a/libdwfl/ChangeLog +++ b/libdwfl/ChangeLog @@ -1,3 +1,9 @@ +2015-01-04 Mark Wielaard <[email protected]> + + * cu.c (intern_cu): Store result and return directly when finding + EOF marker. + (__libdwfl_nextcu): Check *nextp as returned by intern_cu isn't -1. + 2014-12-27 Mark Wielaard <[email protected]> * dwfl_module_getsrc.c (dwfl_module_getsrc): Never match a line that diff --git a/libdwfl/cu.c b/libdwfl/cu.c index 5ce531b..3ac341e 100644 --- a/libdwfl/cu.c +++ b/libdwfl/cu.c @@ -1,5 +1,5 @@ /* Keeping track of DWARF compilation units in libdwfl. - Copyright (C) 2005-2010 Red Hat, Inc. + Copyright (C) 2005-2010, 2015 Red Hat, Inc. This file is part of elfutils. This file is free software; you can redistribute it and/or modify @@ -186,8 +186,9 @@ intern_cu (Dwfl_Module *mod, Dwarf_Off cuoff, struct dwfl_cu **result) { /* This is the EOF marker. Now we have interned all the CUs. One increment in MOD->lazycu counts not having hit EOF yet. */ - *found = (void *) -1l; + *found = *result = (void *) -1; less_lazy (mod); + return DWFL_E_NOERROR; } else { @@ -275,7 +276,8 @@ __libdwfl_nextcu (Dwfl_Module *mod, struct dwfl_cu *lastcu, if (result != DWFL_E_NOERROR) return result; - if ((*nextp)->next == NULL && nextoff == (Dwarf_Off) -1l) + if (*nextp != (void *) -1 + && (*nextp)->next == NULL && nextoff == (Dwarf_Off) -1l) (*nextp)->next = (void *) -1l; } -- 1.8.3.1
