When a struct btrfs_fs_devices was being torn down by
btrfs_close_devices(), there was an invalidated pointer in the global
list fs_uuids which still pointed to it; if a device was closed and
then reopened (which btrfs-convert does), freed memory would be
accessed.
This was found using ThreadSanitizer (pretty much doing what
AddressSanitizer would, but not exiting after the first failure).
To reproduce, build with -fsanitize=thread and run 'make test'.
Representative output is below.
This change makes the current tests TSan-clean.
WARNING: ThreadSanitizer: heap-use-after-free (pid=29161)
Read of size 8 at 0x7d180000eee0 by main thread:
#0 memcmp ??:0
#1 find_fsid .../volumes.c:81
#2 device_list_add .../volumes.c:95
#3 btrfs_scan_one_device .../volumes.c:259
#4 btrfs_scan_fs_devices .../disk-io.c:1002
#5 __open_ctree_fd .../disk-io.c:1090
#6 open_ctree_fd .../disk-io.c:1191
#7 do_convert .../btrfs-convert.c:2317
#8 main .../btrfs-convert.c:2745
Previous write of size 8 at 0x7d180000eee0 by main thread:
#0 free ??:0
#1 btrfs_close_devices .../volumes.c:191
#2 close_ctree .../disk-io.c:1401
#3 do_convert .../btrfs-convert.c:2300
#4 main .../btrfs-convert.c:2745
Location is heap block of size 96 at 0x7d180000eee0 allocated by main thread:
#0 calloc ??:0 (exe+0x00000002acc6)
#1 device_list_add .../volumes.c:97
#2 btrfs_scan_one_device .../volumes.c:259
#3 btrfs_scan_fs_devices .../disk-io.c:1002
#4 __open_ctree_fd .../disk-io.c:1090
#5 open_ctree_fd .../disk-io.c:1191
#6 do_convert .../btrfs-convert.c:2256
#7 main .../btrfs-convert.c:2745
Signed-off-by: Adam Buchbinder <[email protected]>
---
volumes.c | 1 +
volumes.h | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/volumes.c b/volumes.c
index a61928c..36f6050 100644
--- a/volumes.c
+++ b/volumes.c
@@ -188,6 +188,7 @@ again:
goto again;
}
+ list_del(&fs_devices->list);
free(fs_devices);
return 0;
}
diff --git a/volumes.h b/volumes.h
index b1ff3d0..2e960b5 100644
--- a/volumes.h
+++ b/volumes.h
@@ -67,7 +67,7 @@ struct btrfs_device {
struct btrfs_fs_devices {
u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
- /* the device with this id has the most recent coyp of the super */
+ /* the device with this id has the most recent copy of the super */
u64 latest_devid;
u64 latest_trans;
u64 lowest_devid;
--
2.0.0.526.g5318336
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