On Mon, Jun 03, 2019 at 09:27:54AM +0800, damenly.su@xxxxxxxxx wrote: > From: Su Yue <Damenly_Su@xxxxxxx> > > As the link reported, btrfs fi sh may crash while a device is removing. > > valgrind reported: > ====================================================================== > ... > ==883== Invalid write of size 8 > ==883== at 0x13C99A: get_device_info (in /usr/bin/btrfs) > ==883== by 0x13D715: get_fs_info (in /usr/bin/btrfs) > ==883== by 0x153B5F: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > ==883== Address 0x4d8c7a0 is 0 bytes after a block of size 12,288 alloc'd > ==883== at 0x483877F: malloc (vg_replace_malloc.c:299) > ==883== by 0x13D861: get_fs_info (in /usr/bin/btrfs) > ==883== by 0x153B5F: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > ==883== > ==883== Invalid write of size 8 > ==883== at 0x13C99D: get_device_info (in /usr/bin/btrfs) > ==883== by 0x13D715: get_fs_info (in /usr/bin/btrfs) > ==883== by 0x153B5F: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > ==883== Address 0x4d8c7a8 is 8 bytes after a block of size 12,288 alloc'd > ==883== at 0x483877F: malloc (vg_replace_malloc.c:299) > ==883== by 0x13D861: get_fs_info (in /usr/bin/btrfs) > ==883== by 0x153B5F: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > ==883== > ==883== Syscall param ioctl(generic) points to unaddressable byte(s) > ==883== at 0x4CA9CBB: ioctl (in /usr/lib/libc-2.29.so) > ==883== by 0x13C9AB: get_device_info (in /usr/bin/btrfs) > ==883== by 0x13D715: get_fs_info (in /usr/bin/btrfs) > ==883== by 0x153B5F: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > ==883== Address 0x4d8c7a0 is 0 bytes after a block of size 12,288 alloc'd > ==883== at 0x483877F: malloc (vg_replace_malloc.c:299) > ==883== by 0x13D861: get_fs_info (in /usr/bin/btrfs) > ==883== by 0x153B5F: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > ==883== > --883-- VALGRIND INTERNAL ERROR: Valgrind received a signal 11 (SIGSEGV) - exiting > --883-- si_code=1; Faulting address: 0x284D8C7B8; sp: 0x1002eb5e50 > > valgrind: the 'impossible' happened: > Killed by fatal signal > > host stacktrace: > ==883== at 0x5805261C: get_bszB_as_is (m_mallocfree.c:303) > ==883== by 0x5805261C: get_bszB (m_mallocfree.c:315) > ==883== by 0x5805261C: vgPlain_arena_malloc (m_mallocfree.c:1799) > ==883== by 0x58005AD2: vgMemCheck_new_block (mc_malloc_wrappers.c:372) > ==883== by 0x58005AD2: vgMemCheck_malloc (mc_malloc_wrappers.c:407) > ==883== by 0x580A7373: do_client_request (scheduler.c:1925) > ==883== by 0x580A7373: vgPlain_scheduler (scheduler.c:1488) > ==883== by 0x580F57A0: thread_wrapper (syswrap-linux.c:103) > ==883== by 0x580F57A0: run_a_thread_NORETURN (syswrap-linux.c:156) > > sched status: > running_tid=1 > > Thread 1: status = VgTs_Runnable (lwpid 883) > ==883== at 0x483877F: malloc (vg_replace_malloc.c:299) > ==883== by 0x1534AA: ??? (in /usr/bin/btrfs) > ==883== by 0x153C49: ??? (in /usr/bin/btrfs) > ==883== by 0x11B0C1: main (in /usr/bin/btrfs) > client stack range: [0x1FFEFFA000 0x1FFF000FFF] client SP: 0x1FFEFFDCE0 > valgrind stack range: [0x1002DB6000 0x1002EB5FFF] top usage: 7520 of 1048576 > > ====================================================================== > > The above log says that invalid write to allocated @di_args happened > in get_device_info() called in get_fs_info(). > > The size of @di_args is allocated according by fi_args->num_devices. > And fi_args->num_devices is *the number of dev_items in chunk_tree*. > However, in the loop to get devices info, btrfs-progs calls ioctl > BTRFS_IOC_DEV_INFO which just finds device in > fs_info->fs_devices->devices. > > Let's look at kernel side. > In btrfs_rm_device(), btrfs_rm_dev_item() causes removal of > related dev_items in chunk_tree. *Do something*. > Then delete the device from device->fs_devices. > > So the case is: > Userspace kernel > > get_fs_info() btrfs_rm_device() > ... > btrfs_rm_dev_item() > > determine fi_args->num_devices and > fi_args->max_id by seraching chunk_tree. > malloc() ... > Loop(Crashed): call get_device_info() by devid > from 1 to fi_args->max_id. > mutex_lock(&fs_devices->device_list_mutex); > list_del_rcu(&device->dev_list); > ... > > In the loop of get_device_info(), get_device_info() still can get info > of the removing device since it's still in fs_info->fs_devices->devices. > Then the iterator value @ndev increaments causes invalid access out of > bounds. > > Solved it by adding the check of @ndev while looping. > > Reported-by: Peter Hjalmarsson <kanelxake@xxxxxxxxx> > Link: https://bugzilla.redhat.com/show_bug.cgi?id=1711787 > Signed-off-by: Su Yue <Damenly_Su@xxxxxxx> Applied, thanks.
