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Disallow sanitize recursing into Extension subtables multiple times 

Fixes https://oss-fuzz.com/v2/testcase-detail/5216838347653120
which is a stack overflow, not by way of infinite recursion, just
being deep.  That's disallowed anyway, so catch it as it happens,
not afterwards.
This commit is contained in:
Behdad Esfahbod 2018-01-15 20:44:10 -05:00
parent bcb6f1ae0a
commit 949f6af289
2 changed files with 5 additions and 4 deletions
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5
src/hb-ot-layout-gsub-table.hh
View File

@ -1272,10 +1272,9 @@ struct SubstLookup : Lookup
{ {
/* The spec says all subtables of an Extension lookup should /* The spec says all subtables of an Extension lookup should
* have the same type, which shall not be the Extension type * have the same type, which shall not be the Extension type
* itself. This is specially important if one has a reverse type! */ * itself (but we already checked for that).
* This is specially important if one has a reverse type! */
unsigned int type = get_subtable (0).u.extension.get_type (); unsigned int type = get_subtable (0).u.extension.get_type ();
if (unlikely (type == SubstLookupSubTable::Extension))
return_trace (false);
unsigned int count = get_subtable_count (); unsigned int count = get_subtable_count ();
for (unsigned int i = 1; i < count; i++) for (unsigned int i = 1; i < count; i++)
if (get_subtable (i).u.extension.get_type () != type) if (get_subtable (i).u.extension.get_type () != type)

4
src/hb-ot-layout-gsubgpos-private.hh
View File

@ -2230,7 +2230,9 @@ struct ExtensionFormat1
inline bool sanitize (hb_sanitize_context_t *c) const inline bool sanitize (hb_sanitize_context_t *c) const
{ {
TRACE_SANITIZE (this); TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && extensionOffset != 0); return_trace (c->check_struct (this) &&
extensionOffset != 0 &&
extensionLookupType != T::LookupSubTable::Extension);
} }
protected: protected: