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Message-ID: <632f447c-fe1a-e6aa-2fda-73669964fc92@ti.com>
Date: Fri, 19 Aug 2022 16:08:13 +0530
From: Kishon Vijay Abraham I <kishon@...com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: Lorenzo Pieralisi <lpieralisi@...nel.org>,
Shunsuke Mie <mie@...l.co.jp>,
Krzysztof Wilczyński <kw@...ux.com>,
Arnd Bergmann <arnd@...db.de>, <linux-pci@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: Re: [PATCH] misc: pci_endpoint_test: Fix
pci_endpoint_test_{copy,write,read}() panic
+Mani
On 17/08/22 16:44, Greg Kroah-Hartman wrote:
> On Wed, Aug 17, 2022 at 02:18:58PM +0530, Kishon Vijay Abraham I wrote:
>> Hi Lorenzo,
>>
>> On 16/08/22 20:24, Lorenzo Pieralisi wrote:
>>> On Tue, Aug 16, 2022 at 12:27:12PM +0200, Greg Kroah-Hartman wrote:
>>>> On Tue, Aug 16, 2022 at 07:06:17PM +0900, Shunsuke Mie wrote:
>>>>> Although dma_map_single() doesn't permit zero length mapping, the each
>>>>> test functions called the function without zero checking.
>>>>>
>>>>> A panic was reported on arm64:
>>>>>
>>>>> [ 60.137988] ------------[ cut here ]------------
>>>>> [ 60.142630] kernel BUG at kernel/dma/swiotlb.c:624!
>>>>> [ 60.147508] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
>>>>> [ 60.152992] Modules linked in: dw_hdmi_cec crct10dif_ce simple_bridge rcar_fdp1 vsp1 rcar_vin videobuf2_vmalloc rcar_csi2 v4l
>>>>> 2_mem2mem videobuf2_dma_contig videobuf2_memops pci_endpoint_test videobuf2_v4l2 videobuf2_common rcar_fcp v4l2_fwnode v4l2_asyn
>>>>> c videodev mc gpio_bd9571mwv max9611 pwm_rcar ccree at24 authenc libdes phy_rcar_gen3_usb3 usb_dmac display_connector pwm_bl
>>>>> [ 60.186252] CPU: 0 PID: 508 Comm: pcitest Not tainted 6.0.0-rc1rpci-dev+ #237
>>>>> [ 60.193387] Hardware name: Renesas Salvator-X 2nd version board based on r8a77951 (DT)
>>>>> [ 60.201302] pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>>>>> [ 60.208263] pc : swiotlb_tbl_map_single+0x2c0/0x590
>>>>> [ 60.213149] lr : swiotlb_map+0x88/0x1f0
>>>>> [ 60.216982] sp : ffff80000a883bc0
>>>>> [ 60.220292] x29: ffff80000a883bc0 x28: 0000000000000000 x27: 0000000000000000
>>>>> [ 60.227430] x26: 0000000000000000 x25: ffff0004c0da20d0 x24: ffff80000a1f77c0
>>>>> [ 60.234567] x23: 0000000000000002 x22: 0001000040000010 x21: 000000007a000000
>>>>> [ 60.241703] x20: 0000000000200000 x19: 0000000000000000 x18: 0000000000000000
>>>>> [ 60.248840] x17: 0000000000000000 x16: 0000000000000000 x15: ffff0006ff7b9180
>>>>> [ 60.255977] x14: ffff0006ff7b9180 x13: 0000000000000000 x12: 0000000000000000
>>>>> [ 60.263113] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
>>>>> [ 60.270249] x8 : 0001000000000010 x7 : ffff0004c6754b20 x6 : 0000000000000000
>>>>> [ 60.277385] x5 : ffff0004c0da2090 x4 : 0000000000000000 x3 : 0000000000000001
>>>>> [ 60.284521] x2 : 0000000040000000 x1 : 0000000000000000 x0 : 0000000040000010
>>>>> [ 60.291658] Call trace:
>>>>> [ 60.294100] swiotlb_tbl_map_single+0x2c0/0x590
>>>>> [ 60.298629] swiotlb_map+0x88/0x1f0
>>>>> [ 60.302115] dma_map_page_attrs+0x188/0x230
>>>>> [ 60.306299] pci_endpoint_test_ioctl+0x5e4/0xd90 [pci_endpoint_test]
>>>>> [ 60.312660] __arm64_sys_ioctl+0xa8/0xf0
>>>>> [ 60.316583] invoke_syscall+0x44/0x108
>>>>> [ 60.320334] el0_svc_common.constprop.0+0xcc/0xf0
>>>>> [ 60.325038] do_el0_svc+0x2c/0xb8
>>>>> [ 60.328351] el0_svc+0x2c/0x88
>>>>> [ 60.331406] el0t_64_sync_handler+0xb8/0xc0
>>>>> [ 60.335587] el0t_64_sync+0x18c/0x190
>>>>> [ 60.339251] Code: 52800013 d2e00414 35fff45c d503201f (d4210000)
>>>>> [ 60.345344] ---[ end trace 0000000000000000 ]---
>>>>>
>>>>> To fix it, this patch adds checkings the payload length if it is zero.
>>>>>
>>>>> Fixes: 343dc693f7b7 ("misc: pci_endpoint_test: Prevent some integer overflows")
>>>>> Signed-off-by: Shunsuke Mie <mie@...l.co.jp>
>>>>> ---
>>>>> drivers/misc/pci_endpoint_test.c | 6 +++---
>>>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
>>>>> index 8f786a225dcf..d45426a73396 100644
>>>>> --- a/drivers/misc/pci_endpoint_test.c
>>>>> +++ b/drivers/misc/pci_endpoint_test.c
>>>>> @@ -364,7 +364,7 @@ static bool pci_endpoint_test_copy(struct pci_endpoint_test *test,
>>>>> }
>>>>>
>>>>> size = param.size;
>>>>> - if (size > SIZE_MAX - alignment)
>>>>> + if (size > SIZE_MAX - alignment || !size)
>>>>> goto err;
>>>>
>>>> Can we test size first? And do it in the ioctl handler in one place so
>>>> you don't have to add it everywhere?
>>>>
>>>> Or have a "validate all parameters" function that you do it in one
>>>> place?
>>>>
>>>> Also, all of these ioctl handlers are wrong, they are returning "0" to
>>>> userspace if they fail, which is not correct at all.
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/pci/pcitest.c
>>> This is bad, thanks Greg for spotting it.
>>>
>>> @Kishon, we have to fix it asap, please let me know if you
>>> can post a patch promptly.
>>
>> The userspace tool (pcitest [1]) that calls these IOCTLS prints "NOT
>> OKAY" on 0 and "OKAY" for 1.
>>
>> I'll change to negative value for error and still keep '0' for data
>> mismatch error?
>
> No, 0 as a return value from a system call means "success". You can not
> redefine it to mean something else for a tiny single kernel driver,
> otherwise so much for consistency.
>
> 0 is success, -ERROR_NUMBER is an error, please read the ioctl man page.
Thanks Greg!
Mani, Would you be able to post a patch fixing it? If not I'll post it
mid next week.
Regards,
Kishon
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