* [committed] Fix memory leak in write_multifile
@ 2021-03-24 17:06 Tom de Vries
0 siblings, 0 replies; only message in thread
From: Tom de Vries @ 2021-03-24 17:06 UTC (permalink / raw)
To: dwz, jakub, mark
Hi,
When building dwz with -fsanitize=address, we run into some memory leaks:
...
$ cp hello 1; ./dwz 1; cp 1 2; ./dwz -m 3 1 2
./dwz: 1: DWARF compression not beneficial - old size 3372 new size 3372
./dwz: 2: DWARF compression not beneficial - old size 3372 new size 3372
=================================================================
==8024==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 432 byte(s) in 6 object(s) allocated from:
#0 0x7f7ab92cc6d8 in __interceptor_calloc \
(/usr/lib64/libasan.so.4+0xdc6d8)
#1 0x475dc1 in htab_try_create hashtab.c:164
#2 0x44c610 in build_abbrevs dwz.c:11230
#3 0x44ee00 in compute_abbrevs dwz.c:11510
#4 0x46f07c in dwz dwz.c:15396
#5 0x474e0d in dwz_files_1 dwz.c:16327
#6 0x475699 in dwz_files dwz.c:16417
#7 0x4759fc in main dwz.c:16458
#8 0x7f7ab8c41349 in __libc_start_main (/lib64/libc.so.6+0x24349)
Indirect leak of 2928 byte(s) in 6 object(s) allocated from:
#0 0x7f7ab92cc6d8 in __interceptor_calloc \
(/usr/lib64/libasan.so.4+0xdc6d8)
#1 0x475de7 in htab_try_create hashtab.c:168
#2 0x44c610 in build_abbrevs dwz.c:11230
#3 0x44ee00 in compute_abbrevs dwz.c:11510
#4 0x46f07c in dwz dwz.c:15396
#5 0x474e0d in dwz_files_1 dwz.c:16327
#6 0x475699 in dwz_files dwz.c:16417
#7 0x4759fc in main dwz.c:16458
#8 0x7f7ab8c41349 in __libc_start_main (/lib64/libc.so.6+0x24349)
SUMMARY: AddressSanitizer: 3360 byte(s) leaked in 12 allocation(s).
...
A more concrete way to show some of the leaks is by using this patch on
build_abbrevs:
...
+ assert (cu->cu_new_abbrev == NULL);
cu->cu_new_abbrev = h;
return 0;
}
...
which triggers here:
...
#4 0x00000000004211b1 in build_abbrevs (cu=0x7ffff65f0e38, t=0x64e640,
ndies=0x7fffffffd81c, vec=0x649280 <ob2>) at dwz.c:11239
#5 0x0000000000421db2 in compute_abbrevs (dso=0x0) at dwz.c:11511
#6 0x000000000042fa2c in write_multifile (dso=0x64c210)
at dwz.c:15104
...
We could just do a htab_delete in build_abbrevs, which takes care of all the
leaks detected by the assert.
But write_multifile drops CUs from the cu list if
cu->cu_die->die_no_multifile == 1, and if a dropped CU has cu->cu_new_abbrev
!= NULL then cu_new_abbrev is still leaked.
Fix this by calling htab_delete in the loop that drops the CUs.
Committed to trunk.
Thanks,
- Tom
Fix memory leak in write_multifile
2021-03-24 Tom de Vries <tdevries@suse.de>
PR dwz/27643
* dwz.c (write_multifile): Clean up cu->cu_new_abbrev to fix memory
leak.
---
dwz.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/dwz.c b/dwz.c
index c115b54..b212d6d 100644
--- a/dwz.c
+++ b/dwz.c
@@ -15092,10 +15092,15 @@ write_multifile (DSO *dso)
dw_cu_ref *cup;
for (cup = &first_cu; *cup && (*cup)->cu_kind != CU_TYPES; )
- if ((*cup)->cu_die->die_no_multifile == 0)
- cup = &(*cup)->cu_next;
- else
- *cup = (*cup)->cu_next;
+ {
+ if ((*cup)->cu_new_abbrev)
+ htab_delete ((*cup)->cu_new_abbrev);
+
+ if ((*cup)->cu_die->die_no_multifile == 0)
+ cup = &(*cup)->cu_next;
+ else
+ *cup = (*cup)->cu_next;
+ }
*cup = NULL;
multifile_mode = MULTIFILE_MODE_WR;
if (tracing)
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2021-03-24 17:06 [committed] Fix memory leak in write_multifile Tom de Vries
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