Hello, On Fri 21-02-20 22:53:13, yangerkun wrote: > Thanks for the patch! And according to the describes, I'd wonder does there > some scenes exits in ext4 can trigger the similar bug? Yes, I suppose ext4 could trigger a similar bug in principle. Honza > On 2020/2/21 17:18, Jan Kara wrote: > > On Thu 20-02-20 21:46:14, wangyan wrote: > > > I found a NULL pointer dereference in ocfs2_block_group_clear_bits(). > > > The running environment: > > > kernel version: 4.19 > > > A cluster with two nodes, 5 luns mounted on two nodes, and do some > > > file operations like dd/fallocate/truncate/rm on every lun with storage > > > network disconnection. > > > > > > The fallocate operation on dm-23-45 caused an null pointer dereference. > > > > > > The information of NULL pointer dereference as follows: > > > [577992.878282] JBD2: Error -5 detected when updating journal superblock for dm-23-45. > > > [577992.878290] Aborting journal on device dm-23-45. > > > ... > > > [577992.890778] JBD2: Error -5 detected when updating journal superblock for dm-24-46. > > > [577992.890908] __journal_remove_journal_head: freeing b_committed_data > > > [577992.890916] (fallocate,88392,52):ocfs2_extend_trans:474 ERROR: status = -30 > > > [577992.890918] __journal_remove_journal_head: freeing b_committed_data > > > [577992.890920] (fallocate,88392,52):ocfs2_rotate_tree_right:2500 ERROR: status = -30 > > > [577992.890922] __journal_remove_journal_head: freeing b_committed_data > > > [577992.890924] (fallocate,88392,52):ocfs2_do_insert_extent:4382 ERROR: status = -30 > > > [577992.890928] (fallocate,88392,52):ocfs2_insert_extent:4842 ERROR: status = -30 > > > [577992.890928] __journal_remove_journal_head: freeing b_committed_data > > > [577992.890930] (fallocate,88392,52):ocfs2_add_clusters_in_btree:4947 ERROR: status = -30 > > > [577992.890933] __journal_remove_journal_head: freeing b_committed_data > > > [577992.890939] __journal_remove_journal_head: freeing b_committed_data > > > [577992.890949] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020 > > > [577992.890950] Mem abort info: > > > [577992.890951] ESR = 0x96000004 > > > [577992.890952] Exception class = DABT (current EL), IL = 32 bits > > > [577992.890952] SET = 0, FnV = 0 > > > [577992.890953] EA = 0, S1PTW = 0 > > > [577992.890954] Data abort info: > > > [577992.890955] ISV = 0, ISS = 0x00000004 > > > [577992.890956] CM = 0, WnR = 0 > > > [577992.890958] user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000f8da07a9 > > > [577992.890960] [0000000000000020] pgd=0000000000000000 > > > [577992.890964] Internal error: Oops: 96000004 [#1] SMP > > > [577992.890965] Process fallocate (pid: 88392, stack limit = 0x00000000013db2fd) > > > [577992.890968] CPU: 52 PID: 88392 Comm: fallocate Kdump: loaded Tainted: G W OE 4.19.36 #1 > > > [577992.890969] Hardware name: Huawei TaiShan 2280 V2/BC82AMDD, BIOS 0.98 08/25/2019 > > > [577992.890971] pstate: 60400009 (nZCv daif +PAN -UAO) > > > [577992.891054] pc : _ocfs2_free_suballoc_bits+0x63c/0x968 [ocfs2] > > > [577992.891082] lr : _ocfs2_free_suballoc_bits+0x618/0x968 [ocfs2] > > > [577992.891084] sp : ffff0000c8e2b810 > > > [577992.891085] x29: ffff0000c8e2b820 x28: 0000000000000000 > > > [577992.891087] x27: 00000000000006f3 x26: ffffa07957b02e70 > > > [577992.891089] x25: ffff807c59d50000 x24: 00000000000006f2 > > > [577992.891091] x23: 0000000000000001 x22: ffff807bd39abc30 > > > [577992.891093] x21: ffff0000811d9000 x20: ffffa07535d6a000 > > > [577992.891097] x19: ffff000001681638 x18: ffffffffffffffff > > > [577992.891098] x17: 0000000000000000 x16: ffff000080a03df0 > > > [577992.891100] x15: ffff0000811d9708 x14: 203d207375746174 > > > [577992.891101] x13: 73203a524f525245 x12: 20373439343a6565 > > > [577992.891103] x11: 0000000000000038 x10: 0101010101010101 > > > [577992.891106] x9 : ffffa07c68a85d70 x8 : 7f7f7f7f7f7f7f7f > > > [577992.891109] x7 : 0000000000000000 x6 : 0000000000000080 > > > [577992.891110] x5 : 0000000000000000 x4 : 0000000000000002 > > > [577992.891112] x3 : ffff000001713390 x2 : 2ff90f88b1c22f00 > > > [577992.891114] x1 : ffff807bd39abc30 x0 : 0000000000000000 > > > [577992.891116] Call trace: > > > [577992.891139] _ocfs2_free_suballoc_bits+0x63c/0x968 [ocfs2] > > > [577992.891162] _ocfs2_free_clusters+0x100/0x290 [ocfs2] > > > [577992.891185] ocfs2_free_clusters+0x50/0x68 [ocfs2] > > > [577992.891206] ocfs2_add_clusters_in_btree+0x198/0x5e0 [ocfs2] > > > [577992.891227] ocfs2_add_inode_data+0x94/0xc8 [ocfs2] > > > [577992.891248] ocfs2_extend_allocation+0x1bc/0x7a8 [ocfs2] > > > [577992.891269] ocfs2_allocate_extents+0x14c/0x338 [ocfs2] > > > [577992.891290] __ocfs2_change_file_space+0x3f8/0x610 [ocfs2] > > > [577992.891309] ocfs2_fallocate+0xe4/0x128 [ocfs2] > > > [577992.891316] vfs_fallocate+0x11c/0x250 > > > [577992.891317] ksys_fallocate+0x54/0x88 > > > [577992.891319] __arm64_sys_fallocate+0x28/0x38 > > > [577992.891323] el0_svc_common+0x78/0x130 > > > [577992.891325] el0_svc_handler+0x38/0x78 > > > [577992.891327] el0_svc+0x8/0xc > > > > > > My analysis process as follows: > > > ocfs2_fallocate > > > __ocfs2_change_file_space > > > ocfs2_allocate_extents > > > ocfs2_extend_allocation > > > ocfs2_add_inode_data > > > ocfs2_add_clusters_in_btree > > > ocfs2_insert_extent > > > ocfs2_do_insert_extent > > > ocfs2_rotate_tree_right > > > ocfs2_extend_rotate_transaction > > > ocfs2_extend_trans > > > jbd2_journal_restart > > > jbd2__journal_restart > > > /* handle->h_transaction is NULL, > > > * is_handle_aborted(handle) is true > > > */ > > > handle->h_transaction = NULL; > > > start_this_handle > > > return -EROFS; > > > ocfs2_free_clusters > > > _ocfs2_free_clusters > > > _ocfs2_free_suballoc_bits > > > ocfs2_block_group_clear_bits > > > ocfs2_journal_access_gd > > > __ocfs2_journal_access > > > jbd2_journal_get_undo_access > > > /* I think jbd2_write_access_granted() will > > > * return true, because do_get_write_access() > > > * will return -EROFS. > > > */ > > > if (jbd2_write_access_granted(...)) return 0; > > > do_get_write_access > > > /* handle->h_transaction is NULL, it will > > > * return -EROFS here, so do_get_write_access() > > > * was not called. > > > */ > > > if (is_handle_aborted(handle)) return -EROFS; > > > /* bh2jh(group_bh) is NULL, caused NULL > > > pointer dereference */ > > > undo_bg = (struct ocfs2_group_desc *) > > > bh2jh(group_bh)->b_committed_data; > > > > > > If handle->h_transaction == NULL, then jbd2_write_access_granted() > > > does not really guarantee that journal_head will stay around, > > > not even speaking of its b_committed_data. The bh2jh(group_bh) > > > can be removed after ocfs2_journal_access_gd() and before call > > > "bh2jh(group_bh)->b_committed_data". So, we should move > > > is_handle_aborted() check from do_get_write_access() into > > > jbd2_journal_get_undo_access() and jbd2_journal_get_write_access() > > > before the call to jbd2_write_access_granted(). > > > > > > Signed-off-by: Yan Wang <wangyan122@xxxxxxxxxx> > > > Reviewed-by: Jun Piao <piaojun@xxxxxxxxxx> > > > > Thanks! The patch looks good to me. You can add: > > > > Reviewed-by: Jan Kara <jack@xxxxxxx> > > > > Honza > > > > > --- > > > fs/jbd2/transaction.c | 8 ++++++-- > > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > > > diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c > > > index 2dd848a743ed..d181948c0390 100644 > > > --- a/fs/jbd2/transaction.c > > > +++ b/fs/jbd2/transaction.c > > > @@ -936,8 +936,6 @@ do_get_write_access(handle_t *handle, struct journal_head *jh, > > > char *frozen_buffer = NULL; > > > unsigned long start_lock, time_lock; > > > > > > - if (is_handle_aborted(handle)) > > > - return -EROFS; > > > journal = transaction->t_journal; > > > > > > jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy); > > > @@ -1189,6 +1187,9 @@ int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh) > > > struct journal_head *jh; > > > int rc; > > > > > > + if (is_handle_aborted(handle)) > > > + return -EROFS; > > > + > > > if (jbd2_write_access_granted(handle, bh, false)) > > > return 0; > > > > > > @@ -1326,6 +1327,9 @@ int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh) > > > struct journal_head *jh; > > > char *committed_data = NULL; > > > > > > + if (is_handle_aborted(handle)) > > > + return -EROFS; > > > + > > > if (jbd2_write_access_granted(handle, bh, true)) > > > return 0; > > > > > > -- > > > 2.19.1 > > > > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
