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From: "mark at klomp dot org" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug libdw/29434] Memory leak in `dwarf_getscopes`
Date: Thu, 04 Aug 2022 15:13:18 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D29434

--- Comment #3 from Mark Wielaard <mark at klomp dot org> ---
(In reply to Pablo Galindo Salgado from comment #2)
> > it could in theory also be zero
>=20
> In this case, the result was 0 (I am working with Matt)

Interesting, I assumed it was on a failure path.
My proposed patch would have been:

diff --git a/libdw/dwarf_getscopes.c b/libdw/dwarf_getscopes.c
index 5662eecf..676d62f3 100644
--- a/libdw/dwarf_getscopes.c
+++ b/libdw/dwarf_getscopes.c
@@ -100,7 +100,7 @@ origin_match (unsigned int depth, struct Dwarf_Die_Chain
*die, void *arg)
   Dwarf_Die *scopes =3D realloc (a->scopes, nscopes * sizeof scopes[0]);
   if (scopes =3D=3D NULL)
     {
-      free (a->scopes);
+      /* a->scopes will be freed by dwarf_getscopes on error.  */
       __libdw_seterrno (DWARF_E_NOMEM);
       return -1;
     }
@@ -198,6 +198,8 @@ dwarf_getscopes (Dwarf_Die *cudie, Dwarf_Addr pc, Dwarf=
_Die
**scopes)

   if (result > 0)
     *scopes =3D a.scopes;
+  else if (result < 0)
+    free (a.scopes);

   return result;
 }

But if the result is zero I don't believe I fully understand yet how the le=
ak
happens.

--=20
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