* tty/vt/keyboard: out of bounds access in do_compute_shiftstate @ 2016-05-29 17:52 Sasha Levin 2016-05-29 19:04 ` Pavel Machek ` (2 more replies) 0 siblings, 3 replies; 5+ messages in thread From: Sasha Levin @ 2016-05-29 17:52 UTC (permalink / raw) To: gregkh, jslaby, pavel, dmitry.torokhov; +Cc: LKML Hi all, I've hit the following while fuzzing with syzkaller inside a KVM tools guest running the latest -next kernel: [ 2662.777566] BUG: KASAN: global-out-of-bounds in do_compute_shiftstate+0x161/0x370 at addr ffffffffb2e686a0 [ 2662.777592] Read of size 2 by task syz-executor/30576 [ 2662.777676] Address belongs to variable plain_map+0x200/0x3540 [ 2662.777727] CPU: 2 PID: 30576 Comm: syz-executor Tainted: G B 4.6.0-next-20160527-sasha-00024-g6ab0dc9-dirty #3098 [ 2662.777792] 1ffff1001635bde7 00000000dc4d92d7 ffff8800b1adefc0 ffffffffa3fd0b37 [ 2662.777826] ffffffff00000002 fffffbfff5deeda4 0000000041b58ab3 ffffffffae8dd830 [ 2662.777862] ffffffffa3fd09c8 ffffffffa23fa2e8 ffff8800b1adef98 ffff8801d42a20f8 [ 2662.777868] Call Trace: [ 2662.777935] dump_stack (lib/dump_stack.c:53) [ 2662.778136] kasan_report_error (include/linux/kasan.h:28 mm/kasan/report.c:211 mm/kasan/report.c:277) [ 2662.778265] __asan_report_load2_noabort (mm/kasan/report.c:317) [ 2662.778318] do_compute_shiftstate (drivers/tty/vt/keyboard.c:386) [ 2662.778332] fn_null (drivers/tty/vt/keyboard.c:625) [ 2662.778345] k_spec (drivers/tty/vt/keyboard.c:645) [ 2662.778361] kbd_event (drivers/tty/vt/keyboard.c:1459 drivers/tty/vt/keyboard.c:1475) [ 2662.778907] input_to_handler (drivers/input/input.c:120 (discriminator 3)) [ 2662.778926] input_pass_values (drivers/input/input.c:148) [ 2662.778944] input_handle_event (drivers/input/input.c:406) [ 2662.779015] input_inject_event (include/linux/rcupdate.h:910 drivers/input/input.c:467) [ 2662.779034] evdev_do_ioctl (drivers/input/evdev.c:1102) [ 2662.779271] evdev_ioctl_handler (drivers/input/evdev.c:1302) [ 2662.779305] evdev_ioctl (drivers/input/evdev.c:1312) [ 2662.779320] do_vfs_ioctl (fs/ioctl.c:44 fs/ioctl.c:674) [ 2662.779463] SyS_ioctl (fs/ioctl.c:689 fs/ioctl.c:680) [ 2662.779511] do_syscall_64 (arch/x86/entry/common.c:350) [ 2662.779530] entry_SYSCALL64_slow_path (arch/x86/entry/entry_64.S:251) [ 2662.779535] Memory state around the buggy address: [ 2662.779566] ffffffffb2e68580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 2662.779579] ffffffffb2e68600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 2662.779589] >ffffffffb2e68680: 00 00 00 00 fa fa fa fa 00 00 00 00 00 00 00 00 [ 2662.779594] ^ [ 2662.779604] ffffffffb2e68700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 2662.779615] ffffffffb2e68780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Thanks, Sasha ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: tty/vt/keyboard: out of bounds access in do_compute_shiftstate 2016-05-29 17:52 tty/vt/keyboard: out of bounds access in do_compute_shiftstate Sasha Levin @ 2016-05-29 19:04 ` Pavel Machek 2016-06-26 18:31 ` Greg KH 2016-06-27 21:27 ` Dmitry Torokhov 2 siblings, 0 replies; 5+ messages in thread From: Pavel Machek @ 2016-05-29 19:04 UTC (permalink / raw) To: Sasha Levin, vojtech; +Cc: gregkh, jslaby, dmitry.torokhov, LKML Hi! (Vojtech added to cc list. This is history.) > I've hit the following while fuzzing with syzkaller inside a KVM tools guest > running the latest -next kernel: What does syzkaller do? Random syscalls? > [ 2662.777566] BUG: KASAN: global-out-of-bounds in do_compute_shiftstate+0x161/0x370 at addr ffffffffb2e686a0 > > [ 2662.777592] Read of size 2 by task syz-executor/30576 > > [ 2662.777676] Address belongs to variable plain_map+0x200/0x3540 > /* * Called after returning from RAW mode or when changing consoles - recompute * shift_down[] and shift_state from key_down[] maybe called when keymap is * undefined, so that shiftkey release is seen. The caller must hold the * kbd_event_lock. */ static void do_compute_shiftstate(void) { unsigned int i, j, 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]) continue; k = i * BITS_PER_LONG; for (j = 0; j < BITS_PER_LONG; j++, k++) { if (!test_bit(k, key_down)) continue; 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); } } } Best regards, Pavel > [ 2662.777727] CPU: 2 PID: 30576 Comm: syz-executor Tainted: G B 4.6.0-next-20160527-sasha-00024-g6ab0dc9-dirty #3098 > > [ 2662.777792] 1ffff1001635bde7 00000000dc4d92d7 ffff8800b1adefc0 ffffffffa3fd0b37 > > [ 2662.777826] ffffffff00000002 fffffbfff5deeda4 0000000041b58ab3 ffffffffae8dd830 > > [ 2662.777862] ffffffffa3fd09c8 ffffffffa23fa2e8 ffff8800b1adef98 ffff8801d42a20f8 > > [ 2662.777868] Call Trace: > > [ 2662.777935] dump_stack (lib/dump_stack.c:53) > [ 2662.778136] kasan_report_error (include/linux/kasan.h:28 mm/kasan/report.c:211 mm/kasan/report.c:277) > [ 2662.778265] __asan_report_load2_noabort (mm/kasan/report.c:317) > [ 2662.778318] do_compute_shiftstate (drivers/tty/vt/keyboard.c:386) > [ 2662.778332] fn_null (drivers/tty/vt/keyboard.c:625) > [ 2662.778345] k_spec (drivers/tty/vt/keyboard.c:645) > [ 2662.778361] kbd_event (drivers/tty/vt/keyboard.c:1459 drivers/tty/vt/keyboard.c:1475) > [ 2662.778907] input_to_handler (drivers/input/input.c:120 (discriminator 3)) > [ 2662.778926] input_pass_values (drivers/input/input.c:148) > [ 2662.778944] input_handle_event (drivers/input/input.c:406) > [ 2662.779015] input_inject_event (include/linux/rcupdate.h:910 drivers/input/input.c:467) > [ 2662.779034] evdev_do_ioctl (drivers/input/evdev.c:1102) > [ 2662.779271] evdev_ioctl_handler (drivers/input/evdev.c:1302) > [ 2662.779305] evdev_ioctl (drivers/input/evdev.c:1312) > [ 2662.779320] do_vfs_ioctl (fs/ioctl.c:44 fs/ioctl.c:674) > [ 2662.779463] SyS_ioctl (fs/ioctl.c:689 fs/ioctl.c:680) > [ 2662.779511] do_syscall_64 (arch/x86/entry/common.c:350) > [ 2662.779530] entry_SYSCALL64_slow_path (arch/x86/entry/entry_64.S:251) > [ 2662.779535] Memory state around the buggy address: > > [ 2662.779566] ffffffffb2e68580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779579] ffffffffb2e68600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779589] >ffffffffb2e68680: 00 00 00 00 fa fa fa fa 00 00 00 00 00 00 00 00 > > [ 2662.779594] ^ > > [ 2662.779604] ffffffffb2e68700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779615] ffffffffb2e68780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > Thanks, > Sasha -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: tty/vt/keyboard: out of bounds access in do_compute_shiftstate 2016-05-29 17:52 tty/vt/keyboard: out of bounds access in do_compute_shiftstate Sasha Levin 2016-05-29 19:04 ` Pavel Machek @ 2016-06-26 18:31 ` Greg KH 2016-06-27 21:27 ` Dmitry Torokhov 2 siblings, 0 replies; 5+ messages in thread From: Greg KH @ 2016-06-26 18:31 UTC (permalink / raw) To: Sasha Levin; +Cc: jslaby, pavel, dmitry.torokhov, LKML On Sun, May 29, 2016 at 01:52:44PM -0400, Sasha Levin wrote: > Hi all, > > I've hit the following while fuzzing with syzkaller inside a KVM tools guest > running the latest -next kernel: > > [ 2662.777566] BUG: KASAN: global-out-of-bounds in do_compute_shiftstate+0x161/0x370 at addr ffffffffb2e686a0 > > [ 2662.777592] Read of size 2 by task syz-executor/30576 > > [ 2662.777676] Address belongs to variable plain_map+0x200/0x3540 > > [ 2662.777727] CPU: 2 PID: 30576 Comm: syz-executor Tainted: G B 4.6.0-next-20160527-sasha-00024-g6ab0dc9-dirty #3098 > > [ 2662.777792] 1ffff1001635bde7 00000000dc4d92d7 ffff8800b1adefc0 ffffffffa3fd0b37 > > [ 2662.777826] ffffffff00000002 fffffbfff5deeda4 0000000041b58ab3 ffffffffae8dd830 > > [ 2662.777862] ffffffffa3fd09c8 ffffffffa23fa2e8 ffff8800b1adef98 ffff8801d42a20f8 > > [ 2662.777868] Call Trace: > > [ 2662.777935] dump_stack (lib/dump_stack.c:53) > [ 2662.778136] kasan_report_error (include/linux/kasan.h:28 mm/kasan/report.c:211 mm/kasan/report.c:277) > [ 2662.778265] __asan_report_load2_noabort (mm/kasan/report.c:317) > [ 2662.778318] do_compute_shiftstate (drivers/tty/vt/keyboard.c:386) > [ 2662.778332] fn_null (drivers/tty/vt/keyboard.c:625) > [ 2662.778345] k_spec (drivers/tty/vt/keyboard.c:645) > [ 2662.778361] kbd_event (drivers/tty/vt/keyboard.c:1459 drivers/tty/vt/keyboard.c:1475) > [ 2662.778907] input_to_handler (drivers/input/input.c:120 (discriminator 3)) > [ 2662.778926] input_pass_values (drivers/input/input.c:148) > [ 2662.778944] input_handle_event (drivers/input/input.c:406) > [ 2662.779015] input_inject_event (include/linux/rcupdate.h:910 drivers/input/input.c:467) > [ 2662.779034] evdev_do_ioctl (drivers/input/evdev.c:1102) > [ 2662.779271] evdev_ioctl_handler (drivers/input/evdev.c:1302) > [ 2662.779305] evdev_ioctl (drivers/input/evdev.c:1312) > [ 2662.779320] do_vfs_ioctl (fs/ioctl.c:44 fs/ioctl.c:674) > [ 2662.779463] SyS_ioctl (fs/ioctl.c:689 fs/ioctl.c:680) > [ 2662.779511] do_syscall_64 (arch/x86/entry/common.c:350) > [ 2662.779530] entry_SYSCALL64_slow_path (arch/x86/entry/entry_64.S:251) > [ 2662.779535] Memory state around the buggy address: > > [ 2662.779566] ffffffffb2e68580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779579] ffffffffb2e68600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779589] >ffffffffb2e68680: 00 00 00 00 fa fa fa fa 00 00 00 00 00 00 00 00 > > [ 2662.779594] ^ > > [ 2662.779604] ffffffffb2e68700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779615] ffffffffb2e68780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Any chance you can get the result of what the fuzzer was trying to send over the ioctl so we could try to track this down? thanks, greg k-h ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: tty/vt/keyboard: out of bounds access in do_compute_shiftstate 2016-05-29 17:52 tty/vt/keyboard: out of bounds access in do_compute_shiftstate Sasha Levin 2016-05-29 19:04 ` Pavel Machek 2016-06-26 18:31 ` Greg KH @ 2016-06-27 21:27 ` Dmitry Torokhov 2016-07-12 3:06 ` Dmitry Torokhov 2 siblings, 1 reply; 5+ messages in thread From: Dmitry Torokhov @ 2016-06-27 21:27 UTC (permalink / raw) To: Sasha Levin; +Cc: gregkh, jslaby, pavel, LKML On Sun, May 29, 2016 at 01:52:44PM -0400, Sasha Levin wrote: > Hi all, > > I've hit the following while fuzzing with syzkaller inside a KVM tools guest > running the latest -next kernel: > > [ 2662.777566] BUG: KASAN: global-out-of-bounds in do_compute_shiftstate+0x161/0x370 at addr ffffffffb2e686a0 > > [ 2662.777592] Read of size 2 by task syz-executor/30576 > > [ 2662.777676] Address belongs to variable plain_map+0x200/0x3540 > > [ 2662.777727] CPU: 2 PID: 30576 Comm: syz-executor Tainted: G B 4.6.0-next-20160527-sasha-00024-g6ab0dc9-dirty #3098 > > [ 2662.777792] 1ffff1001635bde7 00000000dc4d92d7 ffff8800b1adefc0 ffffffffa3fd0b37 > > [ 2662.777826] ffffffff00000002 fffffbfff5deeda4 0000000041b58ab3 ffffffffae8dd830 > > [ 2662.777862] ffffffffa3fd09c8 ffffffffa23fa2e8 ffff8800b1adef98 ffff8801d42a20f8 > > [ 2662.777868] Call Trace: > > [ 2662.777935] dump_stack (lib/dump_stack.c:53) > [ 2662.778136] kasan_report_error (include/linux/kasan.h:28 mm/kasan/report.c:211 mm/kasan/report.c:277) > [ 2662.778265] __asan_report_load2_noabort (mm/kasan/report.c:317) > [ 2662.778318] do_compute_shiftstate (drivers/tty/vt/keyboard.c:386) > [ 2662.778332] fn_null (drivers/tty/vt/keyboard.c:625) > [ 2662.778345] k_spec (drivers/tty/vt/keyboard.c:645) > [ 2662.778361] kbd_event (drivers/tty/vt/keyboard.c:1459 drivers/tty/vt/keyboard.c:1475) > [ 2662.778907] input_to_handler (drivers/input/input.c:120 (discriminator 3)) > [ 2662.778926] input_pass_values (drivers/input/input.c:148) > [ 2662.778944] input_handle_event (drivers/input/input.c:406) > [ 2662.779015] input_inject_event (include/linux/rcupdate.h:910 drivers/input/input.c:467) > [ 2662.779034] evdev_do_ioctl (drivers/input/evdev.c:1102) > [ 2662.779271] evdev_ioctl_handler (drivers/input/evdev.c:1302) > [ 2662.779305] evdev_ioctl (drivers/input/evdev.c:1312) > [ 2662.779320] do_vfs_ioctl (fs/ioctl.c:44 fs/ioctl.c:674) > [ 2662.779463] SyS_ioctl (fs/ioctl.c:689 fs/ioctl.c:680) > [ 2662.779511] do_syscall_64 (arch/x86/entry/common.c:350) > [ 2662.779530] entry_SYSCALL64_slow_path (arch/x86/entry/entry_64.S:251) > [ 2662.779535] Memory state around the buggy address: > > [ 2662.779566] ffffffffb2e68580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779579] ffffffffb2e68600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779589] >ffffffffb2e68680: 00 00 00 00 fa fa fa fa 00 00 00 00 00 00 00 00 > > [ 2662.779594] ^ > > [ 2662.779604] ffffffffb2e68700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > [ 2662.779615] ffffffffb2e68780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 I think this happens because keymap size in keyboard.c is smaller than keymaps in input devices. Does the patch below fixes this? Thanks. -- Dmitry tty/vt/keyboard: fix OOB access in do_compute_shiftstate() From: Dmitry Torokhov <dmitry.torokhov@gmail.com> 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> Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- drivers/tty/vt/keyboard.c | 30 +++++++++--------------------- 1 file changed, 9 insertions(+), 21 deletions(-) diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index f973bfc..1e93a37 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -366,34 +366,22 @@ 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); } } ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: tty/vt/keyboard: out of bounds access in do_compute_shiftstate 2016-06-27 21:27 ` Dmitry Torokhov @ 2016-07-12 3:06 ` Dmitry Torokhov 0 siblings, 0 replies; 5+ messages in thread From: Dmitry Torokhov @ 2016-07-12 3:06 UTC (permalink / raw) To: Sasha Levin; +Cc: gregkh, jslaby, pavel, LKML On Mon, Jun 27, 2016 at 02:27:56PM -0700, Dmitry Torokhov wrote: > On Sun, May 29, 2016 at 01:52:44PM -0400, Sasha Levin wrote: > > Hi all, > > > > I've hit the following while fuzzing with syzkaller inside a KVM tools guest > > running the latest -next kernel: > > > > [ 2662.777566] BUG: KASAN: global-out-of-bounds in do_compute_shiftstate+0x161/0x370 at addr ffffffffb2e686a0 > > > > [ 2662.777592] Read of size 2 by task syz-executor/30576 > > > > [ 2662.777676] Address belongs to variable plain_map+0x200/0x3540 > > > > [ 2662.777727] CPU: 2 PID: 30576 Comm: syz-executor Tainted: G B 4.6.0-next-20160527-sasha-00024-g6ab0dc9-dirty #3098 > > > > [ 2662.777792] 1ffff1001635bde7 00000000dc4d92d7 ffff8800b1adefc0 ffffffffa3fd0b37 > > > > [ 2662.777826] ffffffff00000002 fffffbfff5deeda4 0000000041b58ab3 ffffffffae8dd830 > > > > [ 2662.777862] ffffffffa3fd09c8 ffffffffa23fa2e8 ffff8800b1adef98 ffff8801d42a20f8 > > > > [ 2662.777868] Call Trace: > > > > [ 2662.777935] dump_stack (lib/dump_stack.c:53) > > [ 2662.778136] kasan_report_error (include/linux/kasan.h:28 mm/kasan/report.c:211 mm/kasan/report.c:277) > > [ 2662.778265] __asan_report_load2_noabort (mm/kasan/report.c:317) > > [ 2662.778318] do_compute_shiftstate (drivers/tty/vt/keyboard.c:386) > > [ 2662.778332] fn_null (drivers/tty/vt/keyboard.c:625) > > [ 2662.778345] k_spec (drivers/tty/vt/keyboard.c:645) > > [ 2662.778361] kbd_event (drivers/tty/vt/keyboard.c:1459 drivers/tty/vt/keyboard.c:1475) > > [ 2662.778907] input_to_handler (drivers/input/input.c:120 (discriminator 3)) > > [ 2662.778926] input_pass_values (drivers/input/input.c:148) > > [ 2662.778944] input_handle_event (drivers/input/input.c:406) > > [ 2662.779015] input_inject_event (include/linux/rcupdate.h:910 drivers/input/input.c:467) > > [ 2662.779034] evdev_do_ioctl (drivers/input/evdev.c:1102) > > [ 2662.779271] evdev_ioctl_handler (drivers/input/evdev.c:1302) > > [ 2662.779305] evdev_ioctl (drivers/input/evdev.c:1312) > > [ 2662.779320] do_vfs_ioctl (fs/ioctl.c:44 fs/ioctl.c:674) > > [ 2662.779463] SyS_ioctl (fs/ioctl.c:689 fs/ioctl.c:680) > > [ 2662.779511] do_syscall_64 (arch/x86/entry/common.c:350) > > [ 2662.779530] entry_SYSCALL64_slow_path (arch/x86/entry/entry_64.S:251) > > [ 2662.779535] Memory state around the buggy address: > > > > [ 2662.779566] ffffffffb2e68580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > [ 2662.779579] ffffffffb2e68600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > [ 2662.779589] >ffffffffb2e68680: 00 00 00 00 fa fa fa fa 00 00 00 00 00 00 00 00 > > > > [ 2662.779594] ^ > > > > [ 2662.779604] ffffffffb2e68700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > [ 2662.779615] ffffffffb2e68780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > I think this happens because keymap size in keyboard.c is smaller than > keymaps in input devices. Does the patch below fixes this? Anyone willing to look it over and add reviewed-by/tested-by? > > Thanks. > > -- > Dmitry > > > tty/vt/keyboard: fix OOB access in do_compute_shiftstate() > > From: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > 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> > Cc: stable@vger.kernel.org > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > --- > drivers/tty/vt/keyboard.c | 30 +++++++++--------------------- > 1 file changed, 9 insertions(+), 21 deletions(-) > > diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c > index f973bfc..1e93a37 100644 > --- a/drivers/tty/vt/keyboard.c > +++ b/drivers/tty/vt/keyboard.c > @@ -366,34 +366,22 @@ 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); > } > } > -- Dmitry ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-07-12 3:06 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-05-29 17:52 tty/vt/keyboard: out of bounds access in do_compute_shiftstate Sasha Levin 2016-05-29 19:04 ` Pavel Machek 2016-06-26 18:31 ` Greg KH 2016-06-27 21:27 ` Dmitry Torokhov 2016-07-12 3:06 ` Dmitry Torokhov
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