BR 2010180: outobj: Garbage may be written in a last PUBDEF
The testcase illustrates the problem. After "nasm -f obj
alonesym.nasm"
let's look to dump:
======
PUBDEF386(91) recnum:5, offset:0000005bh, len:03f9h, chksum:bbh(bb)
Group: 0, Seg: 1
00020000h - 'sym0000' Type:0
00020004h - 'sym0001' Type:0
....
00020134h - 'sym0077' Type:0
PUBDEF(90) recnum:6, offset:00000457h, len:000ah, chksum:b6h(b6)
Group: 0, Seg: 1
00000138h - 's' Type:2
0000b600h - '' Type:0
======
The problem is while 's' offset is 20138h it is marked as type 90h not
91h. The root cause is located in obj_x():
static ObjRecord *obj_x(ObjRecord * orp, uint32_t val)
{
if (orp->type & 1)
orp->x_size = 32;
if (val > 0xFFFF)
orp = obj_force(orp, 32);
if (orp->x_size == 32)
return (obj_dword(orp, val));
orp->x_size = 16;
return (obj_word(orp, val));
}
It sets up x_size and than writes data. In the testcase data are the
offset and this offset overflows a record. In this case the record is
emitted and its x_size is cleared. Because this is last PUBDEF the new
record with only 's' symbol is emitted also but its x_size is not 32
(it's still zero) so obj_fwrite doesn't switch to 91h type.
The problem seems to be very generic and expected to be occurred on
many other record types as well.
----
And the fix is simple:
if (orp->x_size == 32)
{
ObjRecord * nxt = obj_dword(orp, val);
nxt->x_size = 32; /* x_size is cleared when a record overflows */
return nxt;
}
This commit is contained in:
Slavik Gnatenko
H. Peter Anvin
parent
4fb7ed0566
commit
1b67bd25b2
2 changed files with 168 additions and 2 deletions
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@ -346,8 +346,11 @@ static ObjRecord *obj_x(ObjRecord * orp, uint32_t val)
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orp->x_size = 32;
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if (val > 0xFFFF)
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orp = obj_force(orp, 32);
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if (orp->x_size == 32)
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return (obj_dword(orp, val));
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if (orp->x_size == 32) {
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ObjRecord *nxt = obj_dword(orp, val);
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nxt->x_size = 32; /* x_size is cleared when a record overflows */
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return nxt;
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}
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orp->x_size = 16;
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return (obj_word(orp, val));
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}
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163
test/alonesym-obj.asm
Normal file
163
test/alonesym-obj.asm
Normal file
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@ -0,0 +1,163 @@
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section DOS32DATA align=16 public use32 FLAT class=DOS32DATA
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global sym0000
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global sym0001
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global sym0002
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global sym0003
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global sym0004
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global sym0005
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global sym0006
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global sym0007
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global sym0008
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global sym0009
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global sym0010
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global sym0011
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global sym0012
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global sym0013
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global sym0014
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global sym0015
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global sym0016
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global sym0017
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global sym0018
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global sym0019
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global sym0020
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global sym0021
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global sym0022
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global sym0023
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global sym0024
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global sym0025
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global sym0026
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global sym0027
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global sym0028
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global sym0029
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global sym0030
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global sym0031
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global sym0032
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global sym0033
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global sym0034
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global sym0035
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global sym0036
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global sym0037
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global sym0038
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global sym0039
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global sym0040
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global sym0041
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global sym0042
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global sym0043
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global sym0044
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global sym0045
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global sym0046
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global sym0047
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global sym0048
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global sym0049
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global sym0050
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global sym0051
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global sym0052
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global sym0053
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global sym0054
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global sym0055
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global sym0056
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global sym0057
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global sym0058
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global sym0059
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global sym0060
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global sym0061
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global sym0062
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global sym0063
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global sym0064
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global sym0065
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global sym0066
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global sym0067
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global sym0068
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global sym0069
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global sym0070
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global sym0071
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global sym0072
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global sym0073
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global sym0074
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global sym0075
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global sym0076
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global sym0077
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global s
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resb 20000h
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sym0000 resd 1
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sym0001 resd 1
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sym0002 resd 1
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sym0003 resd 1
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sym0004 resd 1
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sym0005 resd 1
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sym0006 resd 1
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sym0007 resd 1
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sym0008 resd 1
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sym0009 resd 1
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sym0010 resd 1
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sym0011 resd 1
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sym0012 resd 1
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sym0013 resd 1
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sym0014 resd 1
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sym0015 resd 1
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sym0016 resd 1
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sym0017 resd 1
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sym0018 resd 1
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sym0019 resd 1
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sym0020 resd 1
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sym0021 resd 1
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sym0022 resd 1
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sym0023 resd 1
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sym0024 resd 1
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sym0025 resd 1
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sym0026 resd 1
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sym0027 resd 1
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sym0028 resd 1
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sym0029 resd 1
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sym0030 resd 1
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sym0031 resd 1
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sym0032 resd 1
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sym0033 resd 1
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sym0034 resd 1
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sym0035 resd 1
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sym0036 resd 1
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sym0037 resd 1
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sym0038 resd 1
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sym0039 resd 1
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sym0040 resd 1
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sym0041 resd 1
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sym0042 resd 1
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sym0043 resd 1
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sym0044 resd 1
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sym0045 resd 1
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sym0046 resd 1
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sym0047 resd 1
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sym0048 resd 1
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sym0049 resd 1
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sym0050 resd 1
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sym0051 resd 1
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sym0052 resd 1
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sym0053 resd 1
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sym0054 resd 1
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sym0055 resd 1
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sym0056 resd 1
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sym0057 resd 1
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sym0058 resd 1
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sym0059 resd 1
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sym0060 resd 1
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sym0061 resd 1
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sym0062 resd 1
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sym0063 resd 1
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sym0064 resd 1
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sym0065 resd 1
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sym0066 resd 1
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sym0067 resd 1
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sym0068 resd 1
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sym0069 resd 1
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sym0070 resd 1
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sym0071 resd 1
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sym0072 resd 1
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sym0073 resd 1
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sym0074 resd 1
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sym0075 resd 1
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sym0076 resd 1
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sym0077 resd 1
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s resd 1
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