Setting invalid value to /sys/devices/system/cpu/cpuX/hotplug/fail
can control `struct cpuhp_step *sp` address, results in the following
global-out-of-bounds read.
Reproducer:
# echo -2 > /sys/devices/system/cpu/cpu0/hotplug/fail
KASAN report:
BUG: KASAN: global-out-of-bounds in write_cpuhp_fail+0x2cd/0x2e0
Read of size 8 at addr ffffffff89734438 by task bash/1941
CPU: 0 PID: 1941 Comm: bash Not tainted 5.2.0-rc6+ #31
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30
04/01/2014
Call Trace:
dump_stack+0xca/0x13e
print_address_description.cold+0x5/0x246
__kasan_report.cold+0x75/0x9a
? write_cpuhp_fail+0x2cd/0x2e0
kasan_report+0xe/0x20
write_cpuhp_fail+0x2cd/0x2e0
? takedown_cpu+0x3a0/0x3a0
? takedown_cpu+0x3a0/0x3a0
dev_attr_store+0x58/0x80
? put_device+0x30/0x30
sysfs_kf_write+0x13d/0x1a0
kernfs_fop_write+0x2bc/0x460
? sysfs_kf_bin_read+0x270/0x270
? kernfs_notify+0x1f0/0x1f0
__vfs_write+0x81/0x100
vfs_write+0x1e1/0x560
ksys_write+0x126/0x250
? __ia32_sys_read+0xb0/0xb0
? do_syscall_64+0x1f/0x390
do_syscall_64+0xc1/0x390
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f05e4f4c970
Code: 73 01 c3 48 8b 0d 28 d5 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44
00 00 83 3d 99 2d 2c 00 04
RSP: 002b:00007ffd7fa630f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f05e4f4c970
RDX: 0000000000000003 RSI: 0000000002039c08 RDI: 0000000000000001
RBP: 0000000002039c08 R08: 00007f05e520c760 R09: 00007f05e5858700
R10: 0000000000000073 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000001 R14: 00007f05e520b600 R15: 0000000000000003
The buggy address belongs to the variable:
cpu_hotplug_lock+0x98/0xa0
Memory state around the buggy address:
ffffffff89734300: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff89734380: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff89734400: 00 00 00 00 fa fa fa fa 00 00 00 00 fa fa fa fa
^
ffffffff89734480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff89734500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Adds sanity check for given value `fail`.
Fixes: 1db49484f21ed ("smp/hotplug: Hotplug state fail injection")
Signed-off-by: Eiichi Tsukata <de...@etsukata.com>
---
kernel/cpu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 077fde6fb953..336254a48502 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1964,6 +1964,9 @@ static ssize_t write_cpuhp_fail(struct device *dev,
if (ret)
return ret;
+ if (fail < CPUHP_OFFLINE || fail > CPUHP_ONLINE)
+ return -EINVAL;
+
/*
* Cannot fail STARTING/DYING callbacks.
*/
--
2.21.0
