[PATCH] binutils: fix out-of-bounds write in stab_xcoff_builtin_type (bz 28694)
Alan Modra
amodra@gmail.com
Wed Dec 15 01:20:42 GMT 2021
On Tue, Dec 14, 2021 at 07:57:32PM +0300, Pavel Mayorov via Binutils wrote:
> I found an out-of-bounds write to the array 'info->xcoff_types' in the
> function 'stab_xcoff_builtin_type' (binutils/stabs.c).
>
> Processing of typenum -34 results in overwriting of adjacent field
> 'info->tags' at line 3668:
> info->xcoff_types[-typenum] = rettype;
>
> This eventually leads to a segmentation fault due to illegal memory
> reference performed by the function 'finish_stab'. ASAN catches this
> as heap-buffer-overflow.
>
> To solve this problem, it is enough to correct the index by which the
> array is accessed: decrease it by 1
Thanks for the patch. I'm going to commit a variation
> + index = -typenum - 1;
because with typenum being a signed int -typenum will overflow and
trigger ubsan warnings if typenum is INT_MIN.
PR 28694
* stabs.c (stab_xcoff_builtin_type): Make typenum unsigned.
Negate typenum earlier, simplifying bounds checking. Correct
off-by-one indexing. Adjust switch cases.
diff --git a/binutils/stabs.c b/binutils/stabs.c
index 274bfb0e7fa..83ee3ea5fa4 100644
--- a/binutils/stabs.c
+++ b/binutils/stabs.c
@@ -202,7 +202,7 @@ static debug_type stab_find_type (void *, struct stab_handle *, const int *);
static bool stab_record_type
(void *, struct stab_handle *, const int *, debug_type);
static debug_type stab_xcoff_builtin_type
- (void *, struct stab_handle *, int);
+ (void *, struct stab_handle *, unsigned int);
static debug_type stab_find_tagged_type
(void *, struct stab_handle *, const char *, int, enum debug_type_kind);
static debug_type *stab_demangle_argtypes
@@ -3496,166 +3496,167 @@ stab_record_type (void *dhandle ATTRIBUTE_UNUSED, struct stab_handle *info,
static debug_type
stab_xcoff_builtin_type (void *dhandle, struct stab_handle *info,
- int typenum)
+ unsigned int typenum)
{
debug_type rettype;
const char *name;
- if (typenum >= 0 || typenum < -XCOFF_TYPE_COUNT)
+ typenum = -typenum - 1;
+ if (typenum >= XCOFF_TYPE_COUNT)
{
- fprintf (stderr, _("Unrecognized XCOFF type %d\n"), typenum);
+ fprintf (stderr, _("Unrecognized XCOFF type %d\n"), -typenum - 1);
return DEBUG_TYPE_NULL;
}
- if (info->xcoff_types[-typenum] != NULL)
- return info->xcoff_types[-typenum];
+ if (info->xcoff_types[typenum] != NULL)
+ return info->xcoff_types[typenum];
- switch (-typenum)
+ switch (typenum)
{
- case 1:
+ case 0:
/* The size of this and all the other types are fixed, defined
by the debugging format. */
name = "int";
rettype = debug_make_int_type (dhandle, 4, false);
break;
- case 2:
+ case 1:
name = "char";
rettype = debug_make_int_type (dhandle, 1, false);
break;
- case 3:
+ case 2:
name = "short";
rettype = debug_make_int_type (dhandle, 2, false);
break;
- case 4:
+ case 3:
name = "long";
rettype = debug_make_int_type (dhandle, 4, false);
break;
- case 5:
+ case 4:
name = "unsigned char";
rettype = debug_make_int_type (dhandle, 1, true);
break;
- case 6:
+ case 5:
name = "signed char";
rettype = debug_make_int_type (dhandle, 1, false);
break;
- case 7:
+ case 6:
name = "unsigned short";
rettype = debug_make_int_type (dhandle, 2, true);
break;
- case 8:
+ case 7:
name = "unsigned int";
rettype = debug_make_int_type (dhandle, 4, true);
break;
- case 9:
+ case 8:
name = "unsigned";
rettype = debug_make_int_type (dhandle, 4, true);
break;
- case 10:
+ case 9:
name = "unsigned long";
rettype = debug_make_int_type (dhandle, 4, true);
break;
- case 11:
+ case 10:
name = "void";
rettype = debug_make_void_type (dhandle);
break;
- case 12:
+ case 11:
/* IEEE single precision (32 bit). */
name = "float";
rettype = debug_make_float_type (dhandle, 4);
break;
- case 13:
+ case 12:
/* IEEE double precision (64 bit). */
name = "double";
rettype = debug_make_float_type (dhandle, 8);
break;
- case 14:
+ case 13:
/* This is an IEEE double on the RS/6000, and different machines
with different sizes for "long double" should use different
negative type numbers. See stabs.texinfo. */
name = "long double";
rettype = debug_make_float_type (dhandle, 8);
break;
- case 15:
+ case 14:
name = "integer";
rettype = debug_make_int_type (dhandle, 4, false);
break;
- case 16:
+ case 15:
name = "boolean";
rettype = debug_make_bool_type (dhandle, 4);
break;
- case 17:
+ case 16:
name = "short real";
rettype = debug_make_float_type (dhandle, 4);
break;
- case 18:
+ case 17:
name = "real";
rettype = debug_make_float_type (dhandle, 8);
break;
- case 19:
+ case 18:
/* FIXME */
name = "stringptr";
rettype = NULL;
break;
- case 20:
+ case 19:
/* FIXME */
name = "character";
rettype = debug_make_int_type (dhandle, 1, true);
break;
- case 21:
+ case 20:
name = "logical*1";
rettype = debug_make_bool_type (dhandle, 1);
break;
- case 22:
+ case 21:
name = "logical*2";
rettype = debug_make_bool_type (dhandle, 2);
break;
- case 23:
+ case 22:
name = "logical*4";
rettype = debug_make_bool_type (dhandle, 4);
break;
- case 24:
+ case 23:
name = "logical";
rettype = debug_make_bool_type (dhandle, 4);
break;
- case 25:
+ case 24:
/* Complex type consisting of two IEEE single precision values. */
name = "complex";
rettype = debug_make_complex_type (dhandle, 8);
break;
- case 26:
+ case 25:
/* Complex type consisting of two IEEE double precision values. */
name = "double complex";
rettype = debug_make_complex_type (dhandle, 16);
break;
- case 27:
+ case 26:
name = "integer*1";
rettype = debug_make_int_type (dhandle, 1, false);
break;
- case 28:
+ case 27:
name = "integer*2";
rettype = debug_make_int_type (dhandle, 2, false);
break;
- case 29:
+ case 28:
name = "integer*4";
rettype = debug_make_int_type (dhandle, 4, false);
break;
- case 30:
+ case 29:
/* FIXME */
name = "wchar";
rettype = debug_make_int_type (dhandle, 2, false);
break;
- case 31:
+ case 30:
name = "long long";
rettype = debug_make_int_type (dhandle, 8, false);
break;
- case 32:
+ case 31:
name = "unsigned long long";
rettype = debug_make_int_type (dhandle, 8, true);
break;
- case 33:
+ case 32:
name = "logical*8";
rettype = debug_make_bool_type (dhandle, 8);
break;
- case 34:
+ case 33:
name = "integer*8";
rettype = debug_make_int_type (dhandle, 8, false);
break;
@@ -3664,9 +3665,7 @@ stab_xcoff_builtin_type (void *dhandle, struct stab_handle *info,
}
rettype = debug_name_type (dhandle, name, rettype);
-
- info->xcoff_types[-typenum] = rettype;
-
+ info->xcoff_types[typenum] = rettype;
return rettype;
}
--
Alan Modra
Australia Development Lab, IBM
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