On 09/12/13 15:56, 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>
---
V3: Simplify the test.
Mark, Dave, I know you had some concerns about other conditions being
tested, but I think those are separate from this fix, which simply ensures
that the level we find for this _NODE block is within the valid range
for a node. (It also matches the test currently present in xfs_check).
Nod.
--Mark.
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