1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
|
https://sourceware.org/PR32934
https://sourceware.org/git/?p=dwz.git;a=commit;h=ed021b829933e5f9ee90587196ba941c30ac832a
From ed021b829933e5f9ee90587196ba941c30ac832a Mon Sep 17 00:00:00 2001
From: Tom de Vries <tdevries@suse.de>
Date: Mon, 12 May 2025 14:01:40 +0200
Subject: [PATCH] Fix double free in compute_abbrevs
PR32934 reports an abort in obstack_free after a double free.
The relevant code is in compute_abbrevs:
...
t = (struct abbrev_tag *)
obstack_alloc (&ob2,
sizeof (*t)
+ (max_nattr + 4) * sizeof (struct abbrev_attr)
+ (max_nattr + 4) * sizeof (int64_t));
...
obstack_free (&ob2, (void *) t);
cuarr = (dw_cu_ref *) obstack_alloc (&ob2, ncus * sizeof (dw_cu_ref));
...
obstack_free (&ob2, (void *) t);
...
The following happens:
- t is allocated
- t is freed
- cuarr is allocated
- t is freed.
Usually, cuarr == t, so effectively cuarr is freed.
But in the case of the PR, cuarr != t, so t is freed twice, triggering the
abort.
Fix this by freeing cuarr instead.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32934
2025-05-12 Tom de Vries <tdevries@suse.de>
* dwz.c (compute_abbrevs): Free cuarr instead of double-freeing t.
---
dwz.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/dwz.c b/dwz.c
index da4121f..a27eb4d 100644
--- a/dwz.c
+++ b/dwz.c
@@ -11813,7 +11813,7 @@ compute_abbrevs (DSO *dso)
}
obstack_free (&ob2, (void *) arr);
}
- obstack_free (&ob2, (void *) t);
+ obstack_free (&ob2, (void *) cuarr);
for (cu = first_cu; cu; cu = cu->cu_next)
{
struct abbrev_tag **arr;
--
2.43.5
|
