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Revert "consolemap: Fix a memory leaking bug in drivers/tty/vt/consolemap.c"

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This reverts commit 84ecc2f6eb.

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: 84ecc2f6eb ("consolemap: Fix a memory leaking bug in drivers/tty/vt/consolemap.c")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ben Hutchings 2019-06-04 19:00:39 +01:00 committed by Greg Kroah-Hartman
parent 888dc273ea
commit 15b3cd8ef4
1 changed files with 1 additions and 5 deletions
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6
drivers/tty/vt/consolemap.c
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@ -489,11 +489,7 @@ con_insert_unipair(struct uni_pagedir *p, u_short unicode, u_short fontpos)
p2 = p1[n = (unicode >> 6) & 0x1f];
if (!p2) {
p2 = p1[n] = kmalloc_array(64, sizeof(u16), GFP_KERNEL);
if (!p2) {
kfree(p1);
p->uni_pgdir[n] = NULL;
return -ENOMEM;
}
if (!p2) return -ENOMEM;
memset(p2, 0xff, 64*sizeof(u16)); /* No glyphs for the characters (yet) */
}