Revision 73223e4e2e3867ebf033a5a8eb2e5df0158ccc99 authored by zhong jiang on 18 August 2017, 22:16:24 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:02 UTC
I hit a use after free issue when executing trinity and repoduced it with KASAN enabled. The related call trace is as follows. BUG: KASan: use after free in SyS_get_mempolicy+0x3c8/0x960 at addr ffff8801f582d766 Read of size 2 by task syz-executor1/798 INFO: Allocated in mpol_new.part.2+0x74/0x160 age=3 cpu=1 pid=799 __slab_alloc+0x768/0x970 kmem_cache_alloc+0x2e7/0x450 mpol_new.part.2+0x74/0x160 mpol_new+0x66/0x80 SyS_mbind+0x267/0x9f0 system_call_fastpath+0x16/0x1b INFO: Freed in __mpol_put+0x2b/0x40 age=4 cpu=1 pid=799 __slab_free+0x495/0x8e0 kmem_cache_free+0x2f3/0x4c0 __mpol_put+0x2b/0x40 SyS_mbind+0x383/0x9f0 system_call_fastpath+0x16/0x1b INFO: Slab 0xffffea0009cb8dc0 objects=23 used=8 fp=0xffff8801f582de40 flags=0x200000000004080 INFO: Object 0xffff8801f582d760 @offset=5984 fp=0xffff8801f582d600 Bytes b4 ffff8801f582d750: ae 01 ff ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ Object ffff8801f582d760: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object ffff8801f582d770: 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkk. Redzone ffff8801f582d778: bb bb bb bb bb bb bb bb ........ Padding ffff8801f582d8b8: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ Memory state around the buggy address: ffff8801f582d600: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801f582d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801f582d700: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fc !shared memory policy is not protected against parallel removal by other thread which is normally protected by the mmap_sem. do_get_mempolicy, however, drops the lock midway while we can still access it later. Early premature up_read is a historical artifact from times when put_user was called in this path see https://lwn.net/Articles/124754/ but that is gone since 8bccd85ffbaf ("[PATCH] Implement sys_* do_* layering in the memory policy layer."). but when we have the the current mempolicy ref count model. The issue was introduced accordingly. Fix the issue by removing the premature release. Link: http://lkml.kernel.org/r/1502950924-27521-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhong jiang <zhongjiang@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> [2.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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isa.txt
===========
ISA Drivers
===========
The following text is adapted from the commit message of the initial
commit of the ISA bus driver authored by Rene Herman.
During the recent "isa drivers using platform devices" discussion it was
pointed out that (ALSA) ISA drivers ran into the problem of not having
the option to fail driver load (device registration rather) upon not
finding their hardware due to a probe() error not being passed up
through the driver model. In the course of that, I suggested a separate
ISA bus might be best; Russell King agreed and suggested this bus could
use the .match() method for the actual device discovery.
The attached does this. For this old non (generically) discoverable ISA
hardware only the driver itself can do discovery so as a difference with
the platform_bus, this isa_bus also distributes match() up to the
driver.
As another difference: these devices only exist in the driver model due
to the driver creating them because it might want to drive them, meaning
that all device creation has been made internal as well.
The usage model this provides is nice, and has been acked from the ALSA
side by Takashi Iwai and Jaroslav Kysela. The ALSA driver module_init's
now (for oldisa-only drivers) become::
static int __init alsa_card_foo_init(void)
{
return isa_register_driver(&snd_foo_isa_driver, SNDRV_CARDS);
}
static void __exit alsa_card_foo_exit(void)
{
isa_unregister_driver(&snd_foo_isa_driver);
}
Quite like the other bus models therefore. This removes a lot of
duplicated init code from the ALSA ISA drivers.
The passed in isa_driver struct is the regular driver struct embedding a
struct device_driver, the normal probe/remove/shutdown/suspend/resume
callbacks, and as indicated that .match callback.
The "SNDRV_CARDS" you see being passed in is a "unsigned int ndev"
parameter, indicating how many devices to create and call our methods
with.
The platform_driver callbacks are called with a platform_device param;
the isa_driver callbacks are being called with a ``struct device *dev,
unsigned int id`` pair directly -- with the device creation completely
internal to the bus it's much cleaner to not leak isa_dev's by passing
them in at all. The id is the only thing we ever want other then the
struct device anyways, and it makes for nicer code in the callbacks as
well.
With this additional .match() callback ISA drivers have all options. If
ALSA would want to keep the old non-load behaviour, it could stick all
of the old .probe in .match, which would only keep them registered after
everything was found to be present and accounted for. If it wanted the
behaviour of always loading as it inadvertently did for a bit after the
changeover to platform devices, it could just not provide a .match() and
do everything in .probe() as before.
If it, as Takashi Iwai already suggested earlier as a way of following
the model from saner buses more closely, wants to load when a later bind
could conceivably succeed, it could use .match() for the prerequisites
(such as checking the user wants the card enabled and that port/irq/dma
values have been passed in) and .probe() for everything else. This is
the nicest model.
To the code...
This exports only two functions; isa_{,un}register_driver().
isa_register_driver() register's the struct device_driver, and then
loops over the passed in ndev creating devices and registering them.
This causes the bus match method to be called for them, which is::
int isa_bus_match(struct device *dev, struct device_driver *driver)
{
struct isa_driver *isa_driver = to_isa_driver(driver);
if (dev->platform_data == isa_driver) {
if (!isa_driver->match ||
isa_driver->match(dev, to_isa_dev(dev)->id))
return 1;
dev->platform_data = NULL;
}
return 0;
}
The first thing this does is check if this device is in fact one of this
driver's devices by seeing if the device's platform_data pointer is set
to this driver. Platform devices compare strings, but we don't need to
do that with everything being internal, so isa_register_driver() abuses
dev->platform_data as a isa_driver pointer which we can then check here.
I believe platform_data is available for this, but if rather not, moving
the isa_driver pointer to the private struct isa_dev is ofcourse fine as
well.
Then, if the the driver did not provide a .match, it matches. If it did,
the driver match() method is called to determine a match.
If it did **not** match, dev->platform_data is reset to indicate this to
isa_register_driver which can then unregister the device again.
If during all this, there's any error, or no devices matched at all
everything is backed out again and the error, or -ENODEV, is returned.
isa_unregister_driver() just unregisters the matched devices and the
driver itself.
module_isa_driver is a helper macro for ISA drivers which do not do
anything special in module init/exit. This eliminates a lot of
boilerplate code. Each module may only use this macro once, and calling
it replaces module_init and module_exit.
max_num_isa_dev is a macro to determine the maximum possible number of
ISA devices which may be registered in the I/O port address space given
the address extent of the ISA devices.
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