Other IDs this deficiency may be known by:
|Date Last Modified
Version Specific Information:
|Cucumber 1.0 i686
||fixed in linux-4.9.60-i686-1 |
|Cucumber 1.0 x86_64
||fixed in linux-4.9.60-x86_64-1 |
|Cucumber 1.1 i686
||fixed in linux-4.9.61-i686-1 |
|Cucumber 1.1 x86_64
||fixed in linux-4.9.61-x86_64-1 |
Author: David Howells
Date: Wed Oct 11 23:32:27 2017 +0100
assoc_array: Fix a buggy node-splitting case
commit ea6789980fdaa610d7eb63602c746bf6ec70cd2b upstream.
This fixes CVE-2017-12193.
Fix a case in the assoc_array implementation in which a new leaf is
added that needs to go into a node that happens to be full, where the
existing leaves in that node cluster together at that level to the
exclusion of new leaf.
What needs to happen is that the existing leaves get moved out to a new
node, N1, at level + 1 and the existing node needs replacing with one,
N0, that has pointers to the new leaf and to N1.
The code that tries to do this gets this wrong in two ways:
(1) The pointer that should've pointed from N0 to N1 is set to point
recursively to N0 instead.
(2) The backpointer from N0 needs to be set correctly in the case N0 is
either the root node or reached through a shortcut.
Fix this by removing this path and using the split_node path instead,
which achieves the same end, but in a more general way (thanks to Eric
Biggers for spotting the redundancy).
The problem manifests itself as:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
Fixes: 3cb989501c26 ("Add a generic associative array implementation.")
Reported-and-tested-by: WU Fan
Signed-off-by: David Howells
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman