[ Upstream commit 33d4a5a7a5b4d02915d765064b2319e90a11cbde ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cpu.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/cpu.c b/kernel/cpu.c index f370a0f43005..d768e15bef83 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1944,6 +1944,9 @@ 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. */