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tty: keyboard, do not speculate on func_table index

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It is very unlikely for processor to speculate on the func_table index.
The index is uchar and func_table is of size 256. So the compiler would
need to screw up and generate a really bad code.

But to stay on the safe side, forbid speculation on this user passed
index.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Kosina <jikos@kernel.org>
Link: https://lore.kernel.org/r/20200730105546.24268-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2020-07-30 12:55:46 +02:00 committed by Greg Kroah-Hartman
parent 7df5081cbf
commit f3af1b68fc
1 changed files with 2 additions and 1 deletions
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3
drivers/tty/vt/keyboard.c
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@ -32,6 +32,7 @@
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/mm.h>
#include <linux/nospec.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/slab.h>
@ -2019,7 +2020,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
goto reterr;
}
kbs->kb_string[sizeof(kbs->kb_string)-1] = '\0';
i = kbs->kb_func;
i = array_index_nospec(kbs->kb_func, MAX_NR_FUNC);
switch (cmd) {
case KDGKBSENT: