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| author | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2016-06-27 14:12:34 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-07-27 09:55:51 -0700 |
| commit | e55e3853f21406d190b4eb54a928345446660aa0 (patch) | |
| tree | f2efb610a7405ff4108f6811126d2594e81bb35b | |
| parent | 93756932e0d49180a56edf56fd8cfb635eae6845 (diff) | |
| download | lwn-e55e3853f21406d190b4eb54a928345446660aa0.tar.gz lwn-e55e3853f21406d190b4eb54a928345446660aa0.zip | |
tty/vt/keyboard: fix OOB access in do_compute_shiftstate()
commit 510cccb5b0c8868a2b302a0ab524da7912da648b upstream.
The size of individual keymap in drivers/tty/vt/keyboard.c is NR_KEYS,
which is currently 256, whereas number of keys/buttons in input device (and
therefor in key_down) is much larger - KEY_CNT - 768, and that can cause
out-of-bound access when we do
sym = U(key_maps[0][k]);
with large 'k'.
To fix it we should not attempt iterating beyond smaller of NR_KEYS and
KEY_CNT.
Also while at it let's switch to for_each_set_bit() instead of open-coding
it.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/vt/keyboard.c | 30 |
1 files changed, 9 insertions, 21 deletions
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index d0e3a4497707..adf4d3124cc6 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -365,34 +365,22 @@ static void to_utf8(struct vc_data *vc, uint c) static void do_compute_shiftstate(void) { - unsigned int i, j, k, sym, val; + unsigned int k, sym, val; shift_state = 0; memset(shift_down, 0, sizeof(shift_down)); - for (i = 0; i < ARRAY_SIZE(key_down); i++) { - - if (!key_down[i]) + for_each_set_bit(k, key_down, min(NR_KEYS, KEY_CNT)) { + sym = U(key_maps[0][k]); + if (KTYP(sym) != KT_SHIFT && KTYP(sym) != KT_SLOCK) continue; - k = i * BITS_PER_LONG; - - for (j = 0; j < BITS_PER_LONG; j++, k++) { - - if (!test_bit(k, key_down)) - continue; + val = KVAL(sym); + if (val == KVAL(K_CAPSSHIFT)) + val = KVAL(K_SHIFT); - sym = U(key_maps[0][k]); - if (KTYP(sym) != KT_SHIFT && KTYP(sym) != KT_SLOCK) - continue; - - val = KVAL(sym); - if (val == KVAL(K_CAPSSHIFT)) - val = KVAL(K_SHIFT); - - shift_down[val]++; - shift_state |= (1 << val); - } + shift_down[val]++; + shift_state |= BIT(val); } } |