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| author | Eiichi Tsukata <devel@etsukata.com> | 2019-06-27 11:47:32 +0900 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-06-27 09:34:04 +0200 |
| commit | 33d4a5a7a5b4d02915d765064b2319e90a11cbde (patch) | |
| tree | 339f50a53535856b69eefed33abf8ac68e4e67e9 | |
| parent | 1bf72720281770162c87990697eae1ba2f1d917a (diff) | |
| download | lwn-33d4a5a7a5b4d02915d765064b2319e90a11cbde.tar.gz lwn-33d4a5a7a5b4d02915d765064b2319e90a11cbde.zip | |
cpu/hotplug: Fix out-of-bounds read when setting fail state
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
Call Trace:
write_cpuhp_fail+0x2cd/0x2e0
dev_attr_store+0x58/0x80
sysfs_kf_write+0x13d/0x1a0
kernfs_fop_write+0x2bc/0x460
vfs_write+0x1e1/0x560
ksys_write+0x126/0x250
do_syscall_64+0xc1/0x390
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f05e4f4c970
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
Add a sanity check for the value written from user space.
Fixes: 1db49484f21ed ("smp/hotplug: Hotplug state fail injection")
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Link: https://lkml.kernel.org/r/20190627024732.31672-1-devel@etsukata.com
| -rw-r--r-- | kernel/cpu.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 551db494f153..ef1c565edc5d 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. */ |