From f6a290686ed62704a1ce571d58a9e1715abe1eb5 Mon Sep 17 00:00:00 2001 From: Adam Buchbinder Date: Fri, 13 Jun 2014 16:43:56 -0700 Subject: [PATCH] btrfs-progs: Fix a use-after-free in the volumes code. 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 Reviewed-by: Satoru Takeuchi Signed-off-by: David Sterba --- volumes.c | 1 + volumes.h | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/volumes.c b/volumes.c index a61928c1..36f60501 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 b1ff3d04..2e960b50 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;