From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Jiri Slaby <jslaby@suse.com>,
Sergei Trofimovich <slyfox@gentoo.org>
Subject: [PATCH 4.9 26/44] tty/vt: fix write/write race in ioctl(KDSKBSENT) handler
Date: Mon, 20 May 2019 14:14:15 +0200 [thread overview]
Message-ID: <20190520115234.061590481@linuxfoundation.org> (raw)
In-Reply-To: <20190520115230.720347034@linuxfoundation.org>
From: Sergei Trofimovich <slyfox@gentoo.org>
commit 46ca3f735f345c9d87383dd3a09fa5d43870770e upstream.
The bug manifests as an attempt to access deallocated memory:
BUG: unable to handle kernel paging request at ffff9c8735448000
#PF error: [PROT] [WRITE]
PGD 288a05067 P4D 288a05067 PUD 288a07067 PMD 7f60c2063 PTE 80000007f5448161
Oops: 0003 [#1] PREEMPT SMP
CPU: 6 PID: 388 Comm: loadkeys Tainted: G C 5.0.0-rc6-00153-g5ded5871030e #91
Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77M-D3H, BIOS F12 11/14/2013
RIP: 0010:__memmove+0x81/0x1a0
Code: 4c 89 4f 10 4c 89 47 18 48 8d 7f 20 73 d4 48 83 c2 20 e9 a2 00 00 00 66 90 48 89 d1 4c 8b 5c 16 f8 4c 8d 54 17 f8 48 c1 e9 03 <f3> 48 a5 4d 89 1a e9 0c 01 00 00 0f 1f 40 00 48 89 d1 4c 8b 1e 49
RSP: 0018:ffffa1b9002d7d08 EFLAGS: 00010203
RAX: ffff9c873541af43 RBX: ffff9c873541af43 RCX: 00000c6f105cd6bf
RDX: 0000637882e986b6 RSI: ffff9c8735447ffb RDI: ffff9c8735447ffb
RBP: ffff9c8739cd3800 R08: ffff9c873b802f00 R09: 00000000fffff73b
R10: ffffffffb82b35f1 R11: 00505b1b004d5b1b R12: 0000000000000000
R13: ffff9c873541af3d R14: 000000000000000b R15: 000000000000000c
FS: 00007f450c390580(0000) GS:ffff9c873f180000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff9c8735448000 CR3: 00000007e213c002 CR4: 00000000000606e0
Call Trace:
vt_do_kdgkb_ioctl+0x34d/0x440
vt_ioctl+0xba3/0x1190
? __bpf_prog_run32+0x39/0x60
? mem_cgroup_commit_charge+0x7b/0x4e0
tty_ioctl+0x23f/0x920
? preempt_count_sub+0x98/0xe0
? __seccomp_filter+0x67/0x600
do_vfs_ioctl+0xa2/0x6a0
? syscall_trace_enter+0x192/0x2d0
ksys_ioctl+0x3a/0x70
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x54/0xe0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The bug manifests on systemd systems with multiple vtcon devices:
# cat /sys/devices/virtual/vtconsole/vtcon0/name
(S) dummy device
# cat /sys/devices/virtual/vtconsole/vtcon1/name
(M) frame buffer device
There systemd runs 'loadkeys' tool in tapallel for each vtcon
instance. This causes two parallel ioctl(KDSKBSENT) calls to
race into adding the same entry into 'func_table' array at:
drivers/tty/vt/keyboard.c:vt_do_kdgkb_ioctl()
The function has no locking around writes to 'func_table'.
The simplest reproducer is to have initrams with the following
init on a 8-CPU machine x86_64:
#!/bin/sh
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
loadkeys -q windowkeys ru4 &
wait
The change adds lock on write path only. Reads are still racy.
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Jiri Slaby <jslaby@suse.com>
Link: https://lkml.org/lkml/2019/2/17/256
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/vt/keyboard.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -121,6 +121,7 @@ static const int NR_TYPES = ARRAY_SIZE(m
static struct input_handler kbd_handler;
static DEFINE_SPINLOCK(kbd_event_lock);
static DEFINE_SPINLOCK(led_lock);
+static DEFINE_SPINLOCK(func_buf_lock); /* guard 'func_buf' and friends */
static unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; /* keyboard key bitmap */
static unsigned char shift_down[NR_SHIFT]; /* shift state counters.. */
static bool dead_key_next;
@@ -1959,11 +1960,12 @@ int vt_do_kdgkb_ioctl(int cmd, struct kb
char *p;
u_char *q;
u_char __user *up;
- int sz;
+ int sz, fnw_sz;
int delta;
char *first_free, *fj, *fnw;
int i, j, k;
int ret;
+ unsigned long flags;
if (!capable(CAP_SYS_TTY_CONFIG))
perm = 0;
@@ -2006,7 +2008,14 @@ int vt_do_kdgkb_ioctl(int cmd, struct kb
goto reterr;
}
+ fnw = NULL;
+ fnw_sz = 0;
+ /* race aginst other writers */
+ again:
+ spin_lock_irqsave(&func_buf_lock, flags);
q = func_table[i];
+
+ /* fj pointer to next entry after 'q' */
first_free = funcbufptr + (funcbufsize - funcbufleft);
for (j = i+1; j < MAX_NR_FUNC && !func_table[j]; j++)
;
@@ -2014,10 +2023,12 @@ int vt_do_kdgkb_ioctl(int cmd, struct kb
fj = func_table[j];
else
fj = first_free;
-
+ /* buffer usage increase by new entry */
delta = (q ? -strlen(q) : 1) + strlen(kbs->kb_string);
+
if (delta <= funcbufleft) { /* it fits in current buf */
if (j < MAX_NR_FUNC) {
+ /* make enough space for new entry at 'fj' */
memmove(fj + delta, fj, first_free - fj);
for (k = j; k < MAX_NR_FUNC; k++)
if (func_table[k])
@@ -2030,20 +2041,28 @@ int vt_do_kdgkb_ioctl(int cmd, struct kb
sz = 256;
while (sz < funcbufsize - funcbufleft + delta)
sz <<= 1;
- fnw = kmalloc(sz, GFP_KERNEL);
- if(!fnw) {
- ret = -ENOMEM;
- goto reterr;
+ if (fnw_sz != sz) {
+ spin_unlock_irqrestore(&func_buf_lock, flags);
+ kfree(fnw);
+ fnw = kmalloc(sz, GFP_KERNEL);
+ fnw_sz = sz;
+ if (!fnw) {
+ ret = -ENOMEM;
+ goto reterr;
+ }
+ goto again;
}
if (!q)
func_table[i] = fj;
+ /* copy data before insertion point to new location */
if (fj > funcbufptr)
memmove(fnw, funcbufptr, fj - funcbufptr);
for (k = 0; k < j; k++)
if (func_table[k])
func_table[k] = fnw + (func_table[k] - funcbufptr);
+ /* copy data after insertion point to new location */
if (first_free > fj) {
memmove(fnw + (fj - funcbufptr) + delta, fj, first_free - fj);
for (k = j; k < MAX_NR_FUNC; k++)
@@ -2056,7 +2075,9 @@ int vt_do_kdgkb_ioctl(int cmd, struct kb
funcbufleft = funcbufleft - delta + sz - funcbufsize;
funcbufsize = sz;
}
+ /* finally insert item itself */
strcpy(func_table[i], kbs->kb_string);
+ spin_unlock_irqrestore(&func_buf_lock, flags);
break;
}
ret = 0;
next prev parent reply other threads:[~2019-05-20 12:18 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 12:13 [PATCH 4.9 00/44] 4.9.178-stable review Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 01/44] net: core: another layer of lists, around PF_MEMALLOC skb handling Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 02/44] locking/rwsem: Prevent decrement of reader count before increment Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 03/44] PCI: hv: Fix a memory leak in hv_eject_device_work() Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 04/44] x86/speculation/mds: Revert CPU buffer clear on double fault exit Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 05/44] x86/speculation/mds: Improve CPU buffer clear documentation Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 06/44] objtool: Fix function fallthrough detection Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 07/44] ARM: exynos: Fix a leaked reference by adding missing of_node_put Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 08/44] power: supply: axp288_charger: Fix unchecked return value Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 09/44] arm64: compat: Reduce address limit Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 10/44] arm64: Clear OSDLR_EL1 on CPU boot Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 11/44] sched/x86: Save [ER]FLAGS on context switch Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 12/44] crypto: chacha20poly1305 - set cra_name correctly Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 13/44] crypto: vmx - fix copy-paste error in CTR mode Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 14/44] crypto: crct10dif-generic - fix use via crypto_shash_digest() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 15/44] crypto: x86/crct10dif-pcl " Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 16/44] ALSA: usb-audio: Fix a memory leak bug Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 17/44] ALSA: hda/hdmi - Read the pin sense from register when repolling Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 18/44] ALSA: hda/hdmi - Consider eld_valid when reporting jack event Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 19/44] ALSA: hda/realtek - EAPD turn on later Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 20/44] ASoC: max98090: Fix restore of DAPM Muxes Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 21/44] ASoC: RT5677-SPI: Disable 16Bit SPI Transfers Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 22/44] mm/mincore.c: make mincore() more conservative Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 23/44] ocfs2: fix ocfs2 read inode data panic in ocfs2_iget Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 24/44] mfd: da9063: Fix OTP control register names to match datasheets for DA9063/63L Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 25/44] mfd: max77620: Fix swapped FPS_PERIOD_MAX_US values Greg Kroah-Hartman
2019-05-20 12:14 ` Greg Kroah-Hartman [this message]
2019-05-20 12:14 ` [PATCH 4.9 27/44] jbd2: check superblock mapped prior to committing Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 28/44] ext4: actually request zeroing of inode table after grow Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 29/44] ext4: fix ext4_show_options for file systems w/o journal Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 30/44] Btrfs: do not start a transaction at iterate_extent_inodes() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 31/44] bcache: fix a race between cache register and cacheset unregister Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 32/44] bcache: never set KEY_PTRS of journal key to 0 in journal_reclaim() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 33/44] ipmi:ssif: compare block number correctly for multi-part return messages Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 34/44] crypto: gcm - Fix error return code in crypto_gcm_create_common() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 35/44] crypto: gcm - fix incompatibility between "gcm" and "gcm_base" Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 36/44] crypto: salsa20 - dont access already-freed walk.iv Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 37/44] crypto: arm/aes-neonbs " Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 38/44] fib_rules: fix error in backport of e9919a24d302 ("fib_rules: return 0...") Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 39/44] writeback: synchronize sync(2) against cgroup writeback membership switches Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 40/44] fs/writeback.c: use rcu_barrier() to wait for inflight wb switches going into workqueue when umount Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 41/44] ext4: zero out the unused memory region in the extent tree block Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 42/44] ext4: fix data corruption caused by overlapping unaligned and aligned IO Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 43/44] ALSA: hda/realtek - Fix for Lenovo B50-70 inverted internal microphone bug Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 44/44] KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes Greg Kroah-Hartman
2019-05-20 19:28 ` [PATCH 4.9 00/44] 4.9.178-stable review kernelci.org bot
2019-05-21 8:51 ` Jon Hunter
2019-05-21 10:34 ` Naresh Kamboju
2019-05-21 16:46 ` Greg Kroah-Hartman
2019-05-21 21:39 ` shuah
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