| Message ID | 20191211050004.18414-4-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 btrfs_reloc_pre_snapshot+0x85/0xc0 [btrfs] > Read of size 4 at addr ffff888157140100 by task btrfs/1822 > > CPU: 2 PID: 1822 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 > check_memory_region+0x13c/0x1b0 > __asan_loadN+0xf/0x20 > btrfs_reloc_pre_snapshot+0x85/0xc0 [btrfs] > create_pending_snapshot+0x209/0x15f0 [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] > Again, we try to access root->reloc_root without verify if that reloc > root is already dead (being freed). > > [FIX] > Check if the root has dead reloc root before accessing it. > > 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 | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c > index 619ccb183515..2d2cd1596ec9 100644 > --- a/fs/btrfs/relocation.c > +++ b/fs/btrfs/relocation.c > @@ -4721,7 +4721,8 @@ void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending, > struct btrfs_root *root = pending->root; > struct reloc_control *rc = root->fs_info->reloc_ctl; > > - if (!root->reloc_root || !rc) > + if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, > + &root->state)) > return; > Same comment here as the other one, you can add Reviewed-by: Josef Bacik <josef@toxicpanda.com> Once it's fixed. Thanks, Josef
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 619ccb183515..2d2cd1596ec9 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4721,7 +4721,8 @@ void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending, struct btrfs_root *root = pending->root; struct reloc_control *rc = root->fs_info->reloc_ctl; - if (!root->reloc_root || !rc) + if (!root->reloc_root || !rc || test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, + &root->state)) return; if (!rc->merge_reloc_tree)
[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 btrfs_reloc_pre_snapshot+0x85/0xc0 [btrfs] Read of size 4 at addr ffff888157140100 by task btrfs/1822 CPU: 2 PID: 1822 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 check_memory_region+0x13c/0x1b0 __asan_loadN+0xf/0x20 btrfs_reloc_pre_snapshot+0x85/0xc0 [btrfs] create_pending_snapshot+0x209/0x15f0 [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] Again, we try to access root->reloc_root without verify if that reloc root is already dead (being freed). [FIX] Check if the root has dead reloc root before accessing it. 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 | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)