15b3cd8ef4
This reverts commit 84ecc2f6eb1cb12e6d44818f94fa49b50f06e6ac.
con_insert_unipair() is working with a sparse 3-dimensional array:
- p->uni_pgdir[] is the top layer
- p1 points to a middle layer
- p2 points to a bottom layer
If it needs to allocate a new middle layer, and then fails to allocate
a new bottom layer, it would previously free only p2, and now it frees
both p1 and p2. But since the new middle layer was already registered
in the top layer, it was not leaked.
However, if it looks up an *existing* middle layer and then fails to
allocate a bottom layer, it now frees both p1 and p2 but does *not*
free any other bottom layers under p1. So it *introduces* a memory
leak.
The error path also cleared the wrong index in p->uni_pgdir[],
introducing a use-after-free.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 84ecc2f6eb1c ("consolemap: Fix a memory leaking bug in drivers/tty/vt/consolemap.c")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.