From: Joe Perches <joe@perches.com>
To: "Schmid, Carsten" <Carsten_Schmid@mentor.com>,
"bp@suse.de" <bp@suse.de>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"mingo@kernel.org" <mingo@kernel.org>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "bhelgaas@google.com" <bhelgaas@google.com>,
"osalvador@suse.de" <osalvador@suse.de>,
"rdunlap@infradead.org" <rdunlap@infradead.org>,
"richardw.yang@linux.intel.com" <richardw.yang@linux.intel.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>
Subject: Re: Resend [PATCH] kernel/resource.c: invalidate parent when freed resource has childs
Date: Fri, 09 Aug 2019 11:37:31 -0700 [thread overview]
Message-ID: <2e93e4057d1f95680bdd6f7f7d754800b7c87ac9.camel@perches.com> (raw)
In-Reply-To: <1565358624103.3694@mentor.com>
On Fri, 2019-08-09 at 13:50 +0000, Schmid, Carsten wrote:
> When a resource is freed and has children, the childrens are
> left without any hint that their parent is no more valid.
> This caused at least one use-after-free in the xhci-hcd using
> ext-caps driver when platform code released platform devices.
>
> Fix this by setting child's parent to zero and warn.
>
> Signed-off-by: Carsten Schmid <carsten_schmid@mentor.com>
> ---
> Rationale:
> When hunting for the root cause of a crash on a 4.14.86 kernel, i
> have found the root cause and checked it being still present
> upstream. Our case:
> Having xhci-hcd and intel_xhci_usb_sw active we can see in
> /proc/meminfo: (exceirpt)
> b3c00000-b3c0ffff : 0000:00:15.0
> b3c00000-b3c0ffff : xhci-hcd
> b3c08070-b3c0846f : intel_xhci_usb_sw
> intel_xhci_usb_sw being a child of xhci-hcd.
>
> Doing an unbind command
> echo 0000:00:15.0 > /sys/bus/pci/drivers/xhci_hcd/unbind
> leads to xhci-hcd being freed in __release_region.
> The intel_xhci_usb_sw resource is accessed in platform code
> in platform_device_del with
> for (i = 0; i < pdev->num_resources; i++) {
> struct resource *r = &pdev->resource[i];
> if (r->parent)
> release_resource(r);
> }
> as the resource's parent has not been updated, the release_resource
> uses the parent:
> p = &old->parent->child;
> which is now invalid.
> Fix this by marking the parent invalid in the child and give a warning
> in dmesg.
> ---
> Advised by Greg (thanks):
> Try resending it with at least the people who get_maintainer.pl says has
> touched that file last in it. [CS:done]
>
> Also, Linus is the unofficial resource.c maintainer. I think he has a
> set of userspace testing scripts for changes somewhere, so you should
> cc: him too. And might as well add me :) [CS:done]
[]
> diff --git a/kernel/resource.c b/kernel/resource.c
[]
> @@ -1200,6 +1200,15 @@ void __release_region(struct resource *parent, resource_size_t start,
> write_unlock(&resource_lock);
> if (res->flags & IORESOURCE_MUXED)
> wake_up(&muxed_resource_wait);
> +
> + write_lock(&resource_lock);
> + if (res->child) {
> + printk(KERN_WARNING "__release_region: %s has child %s,"
> + "invalidating childs parent\n",
> + res->name, res->child->name);
Please coalesce the format because there is likely an unintentional
missing space after the comma, and use pr_warn, %s and __func__
pr_warn("%s: %s has child %s, invalidating child's parent\n",
__func__, res->name, res->child->name);
next prev parent reply other threads:[~2019-08-09 18:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 15:40 [PATCH] kernel/resource.c: invalidate parent when freed resource has childs Schmid, Carsten
2019-08-09 13:50 ` Resend " Schmid, Carsten
2019-08-09 16:59 ` Dan Williams
2019-08-09 18:37 ` Joe Perches [this message]
2019-08-09 18:54 ` [PATCH] kernel/resource.c: Convert printks to pr_<level> Joe Perches
2019-08-09 20:09 ` Resend [PATCH] kernel/resource.c: invalidate parent when freed resource has childs Linus Torvalds
2019-08-09 22:38 ` Wei Yang
2019-08-09 22:45 ` Linus Torvalds
2019-08-10 0:44 ` Wei Yang
2019-08-12 8:39 ` AW: " Schmid, Carsten
2019-08-13 8:09 ` Schmid, Carsten
2019-08-14 14:48 ` [PATCH v2] " Schmid, Carsten
2019-08-14 16:29 ` Wei Yang
2019-08-15 8:18 ` AW: " Schmid, Carsten
2019-08-15 13:03 ` Wei Yang
2019-08-15 13:17 ` AW: " Schmid, Carsten
2019-08-16 10:18 ` [PATCH] kernel/resource.c: warn if released region has children Schmid, Carsten
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