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[Nasm-cvs] BR 2010180: outobj: Garbage may be written in a last PUBDEF
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From: Slavik G. <mo...@us...> - 2008-07-20 02:30:45
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Date: Sat, 19 Jul 2008 19:27:41 -0700
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;
}
---
output/outobj.c | 7 ++-
test/alonesym-obj.asm | 163 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 168 insertions(+), 2 deletions(-)
create mode 100644 test/alonesym-obj.asm
diff --git a/output/outobj.c b/output/outobj.c
index 9ca368d..e248ac3 100644
--- a/output/outobj.c
+++ b/output/outobj.c
@@ -346,8 +346,11 @@ static ObjRecord *obj_x(ObjRecord * orp, uint32_t val)
orp->x_size = 32;
if (val > 0xFFFF)
orp = obj_force(orp, 32);
- if (orp->x_size == 32)
- return (obj_dword(orp, val));
+ 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;
+ }
orp->x_size = 16;
return (obj_word(orp, val));
}
diff --git a/test/alonesym-obj.asm b/test/alonesym-obj.asm
new file mode 100644
index 0000000..6be4d5d
--- /dev/null
+++ b/test/alonesym-obj.asm
@@ -0,0 +1,163 @@
+section DOS32DATA align=16 public use32 FLAT class=DOS32DATA
+
+ global sym0000
+ global sym0001
+ global sym0002
+ global sym0003
+ global sym0004
+ global sym0005
+ global sym0006
+ global sym0007
+ global sym0008
+ global sym0009
+ global sym0010
+ global sym0011
+ global sym0012
+ global sym0013
+ global sym0014
+ global sym0015
+ global sym0016
+ global sym0017
+ global sym0018
+ global sym0019
+ global sym0020
+ global sym0021
+ global sym0022
+ global sym0023
+ global sym0024
+ global sym0025
+ global sym0026
+ global sym0027
+ global sym0028
+ global sym0029
+ global sym0030
+ global sym0031
+ global sym0032
+ global sym0033
+ global sym0034
+ global sym0035
+ global sym0036
+ global sym0037
+ global sym0038
+ global sym0039
+ global sym0040
+ global sym0041
+ global sym0042
+ global sym0043
+ global sym0044
+ global sym0045
+ global sym0046
+ global sym0047
+ global sym0048
+ global sym0049
+ global sym0050
+ global sym0051
+ global sym0052
+ global sym0053
+ global sym0054
+ global sym0055
+ global sym0056
+ global sym0057
+ global sym0058
+ global sym0059
+ global sym0060
+ global sym0061
+ global sym0062
+ global sym0063
+ global sym0064
+ global sym0065
+ global sym0066
+ global sym0067
+ global sym0068
+ global sym0069
+ global sym0070
+ global sym0071
+ global sym0072
+ global sym0073
+ global sym0074
+ global sym0075
+ global sym0076
+ global sym0077
+ global s
+
+
+ resb 20000h
+sym0000 resd 1
+sym0001 resd 1
+sym0002 resd 1
+sym0003 resd 1
+sym0004 resd 1
+sym0005 resd 1
+sym0006 resd 1
+sym0007 resd 1
+sym0008 resd 1
+sym0009 resd 1
+sym0010 resd 1
+sym0011 resd 1
+sym0012 resd 1
+sym0013 resd 1
+sym0014 resd 1
+sym0015 resd 1
+sym0016 resd 1
+sym0017 resd 1
+sym0018 resd 1
+sym0019 resd 1
+sym0020 resd 1
+sym0021 resd 1
+sym0022 resd 1
+sym0023 resd 1
+sym0024 resd 1
+sym0025 resd 1
+sym0026 resd 1
+sym0027 resd 1
+sym0028 resd 1
+sym0029 resd 1
+sym0030 resd 1
+sym0031 resd 1
+sym0032 resd 1
+sym0033 resd 1
+sym0034 resd 1
+sym0035 resd 1
+sym0036 resd 1
+sym0037 resd 1
+sym0038 resd 1
+sym0039 resd 1
+sym0040 resd 1
+sym0041 resd 1
+sym0042 resd 1
+sym0043 resd 1
+sym0044 resd 1
+sym0045 resd 1
+sym0046 resd 1
+sym0047 resd 1
+sym0048 resd 1
+sym0049 resd 1
+sym0050 resd 1
+sym0051 resd 1
+sym0052 resd 1
+sym0053 resd 1
+sym0054 resd 1
+sym0055 resd 1
+sym0056 resd 1
+sym0057 resd 1
+sym0058 resd 1
+sym0059 resd 1
+sym0060 resd 1
+sym0061 resd 1
+sym0062 resd 1
+sym0063 resd 1
+sym0064 resd 1
+sym0065 resd 1
+sym0066 resd 1
+sym0067 resd 1
+sym0068 resd 1
+sym0069 resd 1
+sym0070 resd 1
+sym0071 resd 1
+sym0072 resd 1
+sym0073 resd 1
+sym0074 resd 1
+sym0075 resd 1
+sym0076 resd 1
+sym0077 resd 1
+s resd 1
--
1.5.5.1
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