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libdw: Check end of attributes list consistently.

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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 <mark@klomp.org>
This commit is contained in:
Mark Wielaard
2018-08-18 19:51:27 +02:00
parent 29e31978ba
commit 6983e59b72
3 changed files with 10 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
libdw/ChangeLog
+7
View File
@@ -1,3 +1,10 @@
2018-08-18 Mark Wielaard <mark@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 <mark@klomp.org>
* dwarf_getaranges.c (dwarf_getaranges.c): Make sure there is enough
libdw/dwarf_getabbrev.c
+1 -1
View File
@@ -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)
libdw/dwarf_hasattr.c
+2 -2
View File
@@ -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)