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authorEiichi Tsukata <devel@etsukata.com>2019-06-27 11:47:32 +0900
committerThomas Gleixner <tglx@linutronix.de>2019-06-27 09:34:04 +0200
commit33d4a5a7a5b4d02915d765064b2319e90a11cbde (patch)
tree339f50a53535856b69eefed33abf8ac68e4e67e9
parent1bf72720281770162c87990697eae1ba2f1d917a (diff)
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cpu/hotplug: Fix out-of-bounds read when setting fail statesmp/urgentsmp-urgent-for-linus
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.c3
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.
*/