dwarf_child (__libdw_find_attr), dwarf_getabbrevattr[_data] and dwarf_getattrs all assume the end of the attribute list is when both the name (code) and form of the attribute are zero.
dwarf_getabbrev (__libdw_getabbrev) and dwarf_hasattr assume the end of the attribute list is when either the name (code) or the form of the attribute is zero. The DWARF spec says: "The series of attribute specifications ends with an entry containing 0 for the name and 0 for the form." So the first check is correct. Make sure dwarf_getabbrev and dwarf_hasattr use the same check. This is important since all other functions expect dwarf_getabbrev (__libdw_getabbrev) to have done a data sanity check of the attribute. So if the ending condition is different it could cause a crash. https://sourceware.org/bugzilla/show_bug.cgi?id=23529 Signed-off-by: Mark Wielaard <m...@klomp.org> --- libdw/ChangeLog | 7 +++++++ libdw/dwarf_getabbrev.c | 2 +- libdw/dwarf_hasattr.c | 4 ++-- 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/libdw/ChangeLog b/libdw/ChangeLog index 472d9228..7cb25923 100644 --- a/libdw/ChangeLog +++ b/libdw/ChangeLog @@ -1,3 +1,10 @@ +2018-08-18 Mark Wielaard <m...@klomp.org> + + * dwarf_getabbrev.c (__libdw_getabbrev): Continue until both name + and form are zero. + * dwarf_hasattr.c (dwarf_hasattr): Stop when both name and form + are zero. + 2018-08-18 Mark Wielaard <m...@klomp.org> * dwarf_getaranges.c (dwarf_getaranges.c): Make sure there is enough diff --git a/libdw/dwarf_getabbrev.c b/libdw/dwarf_getabbrev.c index 988d12c2..6a7e981b 100644 --- a/libdw/dwarf_getabbrev.c +++ b/libdw/dwarf_getabbrev.c @@ -140,7 +140,7 @@ __libdw_getabbrev (Dwarf *dbg, struct Dwarf_CU *cu, Dwarf_Off offset, get_sleb128 (formval, abbrevp, end); } } - while (attrname != 0 && attrform != 0); + while (attrname != 0 || attrform != 0); /* Return the length to the caller if she asked for it. */ if (lengthp != NULL) diff --git a/libdw/dwarf_hasattr.c b/libdw/dwarf_hasattr.c index 90053b13..eca08394 100644 --- a/libdw/dwarf_hasattr.c +++ b/libdw/dwarf_hasattr.c @@ -60,8 +60,8 @@ dwarf_hasattr (Dwarf_Die *die, unsigned int search_name) unsigned int attr_form; get_uleb128_unchecked (attr_form, attrp); - /* We can stop if we found the attribute with value zero. */ - if (attr_name == 0 || attr_form == 0) + /* We can stop if we found the end of the attribute list. */ + if (attr_name == 0 && attr_form == 0) return 0; if (attr_name == search_name) -- 2.18.0
