On 09/10/13 10:51, Eric Sandeen wrote:
In traverse_int_dir2block(), the variable 'i' is the level in the tree, with 0 being a leaf node. In the "do" loop we start at the root, and work our way down to a leaf. If the first node we read is an interior node with NODE_MAGIC, but it tells us that its level is 0 (a leaf), this is clearly an inconsistency. Worse, we'd return with success, bno set, and only level[0] in the cursor initialized. Then down this path we'll segfault when accessing an uninitialized (and zeroed) member of the cursor's level array: process_node_dir2 traverse_int_dir2block // returns 0 w/ bno set, only level[0] init'd process_leaf_level_dir2 verify_dir2_path(mp, da_cursor, 0) // p_level == 0 this_level = p_level + 1; node = cursor->level[this_level].bp->b_addr; // level[1] uninit& 0'd Fix this by recognizing that an interior node w/ level 0 is invalid, and error out as for other inconsistencies. By the time the level 0 test is done, we have already ensured that this block has XFS_DA[3]_NODE_MAGIC. Reported-by: Jan Yves Brueckner<jyb@xxxxxxx> Signed-off-by: Eric Sandeen<sandeen@xxxxxxxxxx> --- V2: Drop re-test of hdr magic which is guaranteed to be NODE at this point. fix "interior inode" - s/b "interior node" My only testcase for this is Jan Yves Brueckner's badly corrupted filesystem image. With this change, we get i.e. : +bad level in interior inode for directory inode 39869938 +corrupt block 6 in directory inode 39869957 + will junk block diff --git a/repair/dir2.c b/repair/dir2.c index 05bd4b7..24db351 100644 --- a/repair/dir2.c +++ b/repair/dir2.c @@ -220,6 +220,15 @@ _("bad record count in inode %" PRIu64 ", count = %d, max = %d\n"), */ if (i == -1) { i = da_cursor->active = nodehdr.level; + /* Tests above ensure that we have NODE_MAGIC here */ + if (i == 0) { + do_warn( +_("bad level 0 in interior node for directory inode %" PRIu64 "\n"), + da_cursor->ino); + libxfs_putbuf(bp); + i = -1; + goto error_out; + } if (i>= XFS_DA_NODE_MAXDEPTH) { do_warn( _("bad header depth for directory inode %" PRIu64 "\n"),
But moving the check out of the (i == -1) block, then the loop can check all the intermediate nodes along the way and also the ending leaf.
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