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Message-ID: <CAL_JsqJ-qx=FffPZgx3tdsUu1_mA=E1+xZs0dY+GeoEuvUEm_Q@mail.gmail.com>
Date: Fri, 9 Aug 2024 09:13:55 -0600
From: Rob Herring <robh@...nel.org>
To: Stefan Wiehler <stefan.wiehler@...ia.com>
Cc: Saravana Kannan <saravanak@...gle.com>, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] of/irq: Prevent device address out-of-bounds read in
interrupt map walk
On Fri, Aug 9, 2024 at 3:03 AM Stefan Wiehler <stefan.wiehler@...ia.com> wrote:
>
> When of_irq_parse_raw() is invoked with a device address smaller than
> the interrupt parent node (from #address-cells property), KASAN detects
> the following out-of-bounds read when populating the initial match table
> (dyndbg="func of_irq_parse_* +p"):
>
> OF: of_irq_parse_one: dev=/soc@...icasso/watchdog, index=0
> OF: parent=/soc@...ci@...000000000/gpio0@17,0, intsize=2
> OF: intspec=4
> OF: of_irq_parse_raw: ipar=/soc@...ci@...000000000/gpio0@17,0, size=2
> OF: -> addrsize=3
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in of_irq_parse_raw+0x2b8/0x8d0
> Read of size 4 at addr ffffff81beca5608 by task bash/764
>
> CPU: 1 PID: 764 Comm: bash Tainted: G O 6.1.67-484c613561-nokia_sm_arm64 #1
> Hardware name: Unknown Unknown Product/Unknown Product, BIOS 2023.01-12.24.03-dirty 01/01/2023
> Call trace:
> dump_backtrace+0xdc/0x130
> show_stack+0x1c/0x30
> dump_stack_lvl+0x6c/0x84
> print_report+0x150/0x448
> kasan_report+0x98/0x140
> __asan_load4+0x78/0xa0
> of_irq_parse_raw+0x2b8/0x8d0
> of_irq_parse_one+0x24c/0x270
> parse_interrupts+0xc0/0x120
> of_fwnode_add_links+0x100/0x2d0
> fw_devlink_parse_fwtree+0x64/0xc0
> device_add+0xb38/0xc30
> of_device_add+0x64/0x90
> of_platform_device_create_pdata+0xd0/0x170
> of_platform_bus_create+0x244/0x600
> of_platform_notify+0x1b0/0x254
> blocking_notifier_call_chain+0x9c/0xd0
> __of_changeset_entry_notify+0x1b8/0x230
> __of_changeset_apply_notify+0x54/0xe4
> of_overlay_fdt_apply+0xc04/0xd94
> ...
>
> The buggy address belongs to the object at ffffff81beca5600
> which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 8 bytes inside of
> 128-byte region [ffffff81beca5600, ffffff81beca5680)
>
> The buggy address belongs to the physical page:
> page:00000000230d3d03 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1beca4
> head:00000000230d3d03 order:1 compound_mapcount:0 compound_pincount:0
> flags: 0x8000000000010200(slab|head|zone=2)
> raw: 8000000000010200 0000000000000000 dead000000000122 ffffff810000c300
> raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffffff81beca5500: 04 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffffff81beca5580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffffff81beca5600: 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ^
> ffffff81beca5680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffffff81beca5700: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
> ==================================================================
> OF: -> got it !
>
> Prevent the out-of-bounds read by copying the device address into a
> buffer of sufficient size.
>
> Signed-off-by: Stefan Wiehler <stefan.wiehler@...ia.com>
> ---
> drivers/of/irq.c | 51 ++++++++++++++++++++++++++++++------------------
> 1 file changed, 32 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index c94203ce65bb3..34fe0593036d8 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -151,6 +151,26 @@ const __be32 *of_irq_parse_imap_parent(const __be32 *imap, int len, struct of_ph
> return imap;
> }
>
> +static u32 of_get_address_cells(struct device_node *node)
> +{
See of_bus_n_addr_cells(). It does the same thing. However, I don't
think you need this. See below.
> + struct device_node *tnode, *old = NULL;
> + const __be32 *tmp;
> +
> + /* Look for this #address-cells. We have to implement the old linux
> + * trick of looking for the parent here as some device-trees rely on it
> + */
> + old = of_node_get(node);
> + do {
> + tmp = of_get_property(old, "#address-cells", NULL);
> + tnode = of_get_parent(old);
> + of_node_put(old);
> + old = tnode;
> + } while (old && tmp == NULL);
> + of_node_put(old);
> + old = NULL;
> + return (tmp == NULL) ? 2 : be32_to_cpu(*tmp);
> +}
> +
> /**
> * of_irq_parse_raw - Low level interrupt tree parsing
> * @addr: address specifier (start of "reg" property of the device) in be32 format
> @@ -167,10 +187,10 @@ const __be32 *of_irq_parse_imap_parent(const __be32 *imap, int len, struct of_ph
> */
> int of_irq_parse_raw(const __be32 *addr, struct of_phandle_args *out_irq)
> {
> - struct device_node *ipar, *tnode, *old = NULL;
> + struct device_node *ipar, *tnode;
> __be32 initial_match_array[MAX_PHANDLE_ARGS];
> const __be32 *match_array = initial_match_array;
> - const __be32 *tmp, dummy_imask[] = { [0 ... MAX_PHANDLE_ARGS] = cpu_to_be32(~0) };
> + const __be32 dummy_imask[] = { [0 ... MAX_PHANDLE_ARGS] = cpu_to_be32(~0) };
> u32 intsize = 1, addrsize;
> int i, rc = -EINVAL;
>
> @@ -201,20 +221,7 @@ int of_irq_parse_raw(const __be32 *addr, struct of_phandle_args *out_irq)
> if (out_irq->args_count != intsize)
> goto fail;
>
> - /* Look for this #address-cells. We have to implement the old linux
> - * trick of looking for the parent here as some device-trees rely on it
> - */
> - old = of_node_get(ipar);
> - do {
> - tmp = of_get_property(old, "#address-cells", NULL);
> - tnode = of_get_parent(old);
> - of_node_put(old);
> - old = tnode;
> - } while (old && tmp == NULL);
> - of_node_put(old);
> - old = NULL;
> - addrsize = (tmp == NULL) ? 2 : be32_to_cpu(*tmp);
> -
> + addrsize = of_get_address_cells(ipar);
> pr_debug(" -> addrsize=%d\n", addrsize);
>
> /* Range check so that the temporary buffer doesn't overflow */
> @@ -343,8 +350,9 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
> {
> struct device_node *p;
> const __be32 *addr;
> - u32 intsize;
> + u32 addrsize, intsize;
> int i, res;
> + __be32 addr_buf[3] = { 0 };
>
> pr_debug("of_irq_parse_one: dev=%pOF, index=%d\n", device, index);
>
> @@ -354,12 +362,17 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
>
> /* Get the reg property (if any) */
> addr = of_get_property(device, "reg", NULL);
NULL here is the length returned. Use that and just copy length/4 or 3
cells, which ever is less.
> + addrsize = of_get_address_cells(device);
> +
> + /* Prevent out-of-bounds read in case of longer interrupt parent address size */
> + if (addr)
> + memcpy(addr_buf, addr, addrsize * sizeof(addrsize));
I find sizeof(addrsize) a bit odd here as it just happens to match,
but it's storage size isn't really related. I would do sizeof(__be32)
instead. Though with the above changes, you'll probably have something
like this:
if (len > (3 * sizeof(__be32))
len = 3 * sizeof(__be32);
Rob
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