Message ID | 20191211050004.18414-3-wqu@suse.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | btrfs: fixes for relocation to avoid KASAN reports | expand |
On 12/11/19 12:00 AM, Qu Wenruo wrote: > [BUG] > When running workload with balance start/cancel, snapshot > creation/deletion and fsstress, we can hit the following KASAN report: > > ================================================================== > BUG: KASAN: use-after-free in create_reloc_root+0x9f/0x460 [btrfs] > Read of size 8 at addr ffff8881571741f0 by task btrfs/3539 > > CPU: 6 PID: 3539 Comm: btrfs Tainted: G O 5.5.0-rc1-custom+ #40 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 > Call Trace: > dump_stack+0xc2/0x11a > print_address_description.constprop.0+0x20/0x210 > __kasan_report.cold+0x1b/0x41 > kasan_report+0x12/0x20 > __asan_load8+0x54/0x90 > create_reloc_root+0x9f/0x460 [btrfs] > btrfs_reloc_post_snapshot+0xff/0x6c0 [btrfs] > create_pending_snapshot+0xa9b/0x15f0 [btrfs] > create_pending_snapshots+0x111/0x140 [btrfs] > btrfs_commit_transaction+0x7a6/0x1360 [btrfs] > btrfs_mksubvol+0x915/0x960 [btrfs] > btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs] > btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs] > btrfs_ioctl+0x241b/0x3e60 [btrfs] > do_vfs_ioctl+0x831/0xb10 > ksys_ioctl+0x67/0x90 > __x64_sys_ioctl+0x43/0x50 > do_syscall_64+0x79/0xe0 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > [CAUSE] > This is another case where root->reloc_root is accessed without checking > if the reloc root is already dead. > > [FIX] > Also check DEAD_RELOC_TREE bit before accessing root->reloc_root. > > Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org> > Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") > Signed-off-by: Qu Wenruo <wqu@suse.com> > --- > fs/btrfs/relocation.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c > index bb41b981e493..619ccb183515 100644 > --- a/fs/btrfs/relocation.c > +++ b/fs/btrfs/relocation.c > @@ -4755,7 +4755,14 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, > struct reloc_control *rc = root->fs_info->reloc_ctl; > int ret; > > - if (!root->reloc_root || !rc) > + /* > + * We don't need to use reloc tree if: > + * - No reloc tree > + * - Relocation not running > + * - Reloc tree already merged > + */ > + if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, > + &root->state)) This is awkward formatting, can we move the test_bit() to the first thing we check so it's less weird? Then you can add Reviewed-by: Josef Bacik <josef@toxicpanda.com> Thanks, Josef
On Wed, Dec 11, 2019 at 09:55:04AM -0500, Josef Bacik wrote: > > + /* > > + * We don't need to use reloc tree if: > > + * - No reloc tree > > + * - Relocation not running > > + * - Reloc tree already merged > > + */ > > + if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, > > + &root->state)) > > This is awkward formatting, can we move the test_bit() to the first thing we > check so it's less weird? Then you can add I had the same thought, will move the test_bit on the next line.
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index bb41b981e493..619ccb183515 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4755,7 +4755,14 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, struct reloc_control *rc = root->fs_info->reloc_ctl; int ret; - if (!root->reloc_root || !rc) + /* + * We don't need to use reloc tree if: + * - No reloc tree + * - Relocation not running + * - Reloc tree already merged + */ + if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, + &root->state)) return 0; rc = root->fs_info->reloc_ctl;
[BUG] When running workload with balance start/cancel, snapshot creation/deletion and fsstress, we can hit the following KASAN report: ================================================================== BUG: KASAN: use-after-free in create_reloc_root+0x9f/0x460 [btrfs] Read of size 8 at addr ffff8881571741f0 by task btrfs/3539 CPU: 6 PID: 3539 Comm: btrfs Tainted: G O 5.5.0-rc1-custom+ #40 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack+0xc2/0x11a print_address_description.constprop.0+0x20/0x210 __kasan_report.cold+0x1b/0x41 kasan_report+0x12/0x20 __asan_load8+0x54/0x90 create_reloc_root+0x9f/0x460 [btrfs] btrfs_reloc_post_snapshot+0xff/0x6c0 [btrfs] create_pending_snapshot+0xa9b/0x15f0 [btrfs] create_pending_snapshots+0x111/0x140 [btrfs] btrfs_commit_transaction+0x7a6/0x1360 [btrfs] btrfs_mksubvol+0x915/0x960 [btrfs] btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs] btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs] btrfs_ioctl+0x241b/0x3e60 [btrfs] do_vfs_ioctl+0x831/0xb10 ksys_ioctl+0x67/0x90 __x64_sys_ioctl+0x43/0x50 do_syscall_64+0x79/0xe0 entry_SYSCALL_64_after_hwframe+0x49/0xbe [CAUSE] This is another case where root->reloc_root is accessed without checking if the reloc root is already dead. [FIX] Also check DEAD_RELOC_TREE bit before accessing root->reloc_root. Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org> Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/relocation.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)