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Re: net/gadget: slab-out-of-bounds write in dev_config

Started byFelipe Balbi <balbi@kernel.org>
First post2016-12-27 12:30 +0100
Last post2016-12-28 13:00 +0100
Articles 3 — 2 participants

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  Re: net/gadget: slab-out-of-bounds write in dev_config Felipe Balbi <balbi@kernel.org> - 2016-12-27 12:30 +0100
    Re: net/gadget: slab-out-of-bounds write in dev_config Alan Stern <stern@rowland.harvard.edu> - 2016-12-27 16:30 +0100
      Re: net/gadget: slab-out-of-bounds write in dev_config Felipe Balbi <balbi@kernel.org> - 2016-12-28 13:00 +0100

#1547566 — Re: net/gadget: slab-out-of-bounds write in dev_config

FromFelipe Balbi <balbi@kernel.org>
Date2016-12-27 12:30 +0100
SubjectRe: net/gadget: slab-out-of-bounds write in dev_config
Message-ID<sSY78-1nC-17@gated-at.bofh.it>

[Multipart message — attachments visible in raw view] — view raw

Hi,

Alan Stern <stern@rowland.harvard.edu> writes:
> On Tue, 6 Dec 2016, Andrey Konovalov wrote:
>
>> Hi!
>> 
>> I've got the following error report while running the syzkaller fuzzer.
>> 
>> ep0_write() doesn't check the length, so a user can cause an
>> out-of-bounds with both size and data controlled.
>> There's a comment which says "IN DATA+STATUS caller makes len <=
>> wLength". While I'm not exactly sure what that means, the length seems
>> to be passed unmodified directly from dev_config().
>
> You're right about the comment being misleading.  It looks like 
> somebody forgot to actually do the check.
>
>> This doesn't seem to be a critical security issue since gadgetfs can't
>> be mounted from a user namespace.
>> 
>> On commit 3c49de52d5647cda8b42c4255cf8a29d1e22eff5 (Dec 2).
>> 
>> ==================================================================
>> BUG: KASAN: slab-out-of-bounds in dev_config+0x86f/0x1190 at addr
>> ffff88003c47e160
>> Write of size 65537 by task syz-executor0/6356
>> CPU: 3 PID: 6356 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #19
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>  ffff88003c107ad8 ffffffff81f96aba ffffffff3dc11ef0 1ffff10007820eee
>>  ffffed0007820ee6 ffff88003dc11f00 0000000041b58ab3 ffffffff8598b4c8
>>  ffffffff81f96828 ffffffff813fb4a0 ffff88003b6eadc0 ffff88003c107738
>> Call Trace:
>>  [<     inline     >] __dump_stack lib/dump_stack.c:15
>>  [<ffffffff81f96aba>] dump_stack+0x292/0x398 lib/dump_stack.c:51
>>  [<ffffffff817e4dec>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:159
>>  [<     inline     >] print_address_description mm/kasan/report.c:197
>>  [<ffffffff817e5080>] kasan_report_error+0x1f0/0x4e0 mm/kasan/report.c:286
>>  [<ffffffff817e5705>] kasan_report+0x35/0x40 mm/kasan/report.c:306
>>  [<     inline     >] check_memory_region_inline mm/kasan/kasan.c:308
>>  [<ffffffff817e3fb9>] check_memory_region+0x139/0x190 mm/kasan/kasan.c:315
>>  [<ffffffff817e4044>] kasan_check_write+0x14/0x20 mm/kasan/kasan.c:326
>>  [<     inline     >] copy_from_user arch/x86/include/asm/uaccess.h:689
>>  [<     inline     >] ep0_write drivers/usb/gadget/legacy/inode.c:1135
>>  [<ffffffff83228caf>] dev_config+0x86f/0x1190
>> drivers/usb/gadget/legacy/inode.c:1759
>>  [<ffffffff817fdd55>] __vfs_write+0x5d5/0x760 fs/read_write.c:510
>>  [<ffffffff817ff650>] vfs_write+0x170/0x4e0 fs/read_write.c:560
>>  [<     inline     >] SYSC_write fs/read_write.c:607
>>  [<ffffffff81803a5b>] SyS_write+0xfb/0x230 fs/read_write.c:599
>>  [<ffffffff84f47ec1>] entry_SYSCALL_64_fastpath+0x1f/0xc2
>
> How does this patch work out?
>
> Alan Stern
>
>
>
> Index: usb-4.x/drivers/usb/gadget/legacy/inode.c
> ===================================================================
> --- usb-4.x.orig/drivers/usb/gadget/legacy/inode.c
> +++ usb-4.x/drivers/usb/gadget/legacy/inode.c
> @@ -1126,7 +1126,7 @@ ep0_write (struct file *fd, const char _
>  	/* data and/or status stage for control request */
>  	} else if (dev->state == STATE_DEV_SETUP) {
>  
> -		/* IN DATA+STATUS caller makes len <= wLength */
> +		len = min(len, (size_t) dev->setup_wLength);
>  		if (dev->setup_in) {
>  			retval = setup_req (dev->gadget->ep0, dev->req, len);
>  			if (retval == 0) {
>

I already have a patch from Greg for this. See [1]

[1] https://git.kernel.org/cgit/linux/kernel/git/balbi/usb.git/commit/?id=230bc0cb8ff222d9f0fbbd93a80393140b39481f

-- 
balbi

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#1547617

FromAlan Stern <stern@rowland.harvard.edu>
Date2016-12-27 16:30 +0100
Message-ID<sT1Ro-3KO-19@gated-at.bofh.it>
In reply to#1547566
On Tue, 27 Dec 2016, Felipe Balbi wrote:

> 
> Hi,
> 
> Alan Stern <stern@rowland.harvard.edu> writes:
> > On Tue, 6 Dec 2016, Andrey Konovalov wrote:
> >
> >> Hi!
> >> 
> >> I've got the following error report while running the syzkaller fuzzer.
> >> 
> >> ep0_write() doesn't check the length, so a user can cause an
> >> out-of-bounds with both size and data controlled.
> >> There's a comment which says "IN DATA+STATUS caller makes len <=
> >> wLength". While I'm not exactly sure what that means, the length seems
> >> to be passed unmodified directly from dev_config().
> >
> > You're right about the comment being misleading.  It looks like 
> > somebody forgot to actually do the check.
> >
> >> This doesn't seem to be a critical security issue since gadgetfs can't
> >> be mounted from a user namespace.
> >> 
> >> On commit 3c49de52d5647cda8b42c4255cf8a29d1e22eff5 (Dec 2).
> >> 
> >> ==================================================================
> >> BUG: KASAN: slab-out-of-bounds in dev_config+0x86f/0x1190 at addr
> >> ffff88003c47e160
> >> Write of size 65537 by task syz-executor0/6356
> >> CPU: 3 PID: 6356 Comm: syz-executor0 Not tainted 4.9.0-rc7+ #19
> >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >>  ffff88003c107ad8 ffffffff81f96aba ffffffff3dc11ef0 1ffff10007820eee
> >>  ffffed0007820ee6 ffff88003dc11f00 0000000041b58ab3 ffffffff8598b4c8
> >>  ffffffff81f96828 ffffffff813fb4a0 ffff88003b6eadc0 ffff88003c107738
> >> Call Trace:
> >>  [<     inline     >] __dump_stack lib/dump_stack.c:15
> >>  [<ffffffff81f96aba>] dump_stack+0x292/0x398 lib/dump_stack.c:51
> >>  [<ffffffff817e4dec>] kasan_object_err+0x1c/0x70 mm/kasan/report.c:159
> >>  [<     inline     >] print_address_description mm/kasan/report.c:197
> >>  [<ffffffff817e5080>] kasan_report_error+0x1f0/0x4e0 mm/kasan/report.c:286
> >>  [<ffffffff817e5705>] kasan_report+0x35/0x40 mm/kasan/report.c:306
> >>  [<     inline     >] check_memory_region_inline mm/kasan/kasan.c:308
> >>  [<ffffffff817e3fb9>] check_memory_region+0x139/0x190 mm/kasan/kasan.c:315
> >>  [<ffffffff817e4044>] kasan_check_write+0x14/0x20 mm/kasan/kasan.c:326
> >>  [<     inline     >] copy_from_user arch/x86/include/asm/uaccess.h:689
> >>  [<     inline     >] ep0_write drivers/usb/gadget/legacy/inode.c:1135
> >>  [<ffffffff83228caf>] dev_config+0x86f/0x1190
> >> drivers/usb/gadget/legacy/inode.c:1759
> >>  [<ffffffff817fdd55>] __vfs_write+0x5d5/0x760 fs/read_write.c:510
> >>  [<ffffffff817ff650>] vfs_write+0x170/0x4e0 fs/read_write.c:560
> >>  [<     inline     >] SYSC_write fs/read_write.c:607
> >>  [<ffffffff81803a5b>] SyS_write+0xfb/0x230 fs/read_write.c:599
> >>  [<ffffffff84f47ec1>] entry_SYSCALL_64_fastpath+0x1f/0xc2
> >
> > How does this patch work out?
> >
> > Alan Stern
> >
> >
> >
> > Index: usb-4.x/drivers/usb/gadget/legacy/inode.c
> > ===================================================================
> > --- usb-4.x.orig/drivers/usb/gadget/legacy/inode.c
> > +++ usb-4.x/drivers/usb/gadget/legacy/inode.c
> > @@ -1126,7 +1126,7 @@ ep0_write (struct file *fd, const char _
> >  	/* data and/or status stage for control request */
> >  	} else if (dev->state == STATE_DEV_SETUP) {
> >  
> > -		/* IN DATA+STATUS caller makes len <= wLength */
> > +		len = min(len, (size_t) dev->setup_wLength);
> >  		if (dev->setup_in) {
> >  			retval = setup_req (dev->gadget->ep0, dev->req, len);
> >  			if (retval == 0) {
> >
> 
> I already have a patch from Greg for this. See [1]
> 
> [1] https://git.kernel.org/cgit/linux/kernel/git/balbi/usb.git/commit/?id=230bc0cb8ff222d9f0fbbd93a80393140b39481f

The two patches fix different problems.  My patch goes on the pathway
where dev->state > STATE_DEV_OPENED in dev_config(), and Greg's patch
handles the case where it is <=.

Alan Stern

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#1547927

FromFelipe Balbi <balbi@kernel.org>
Date2016-12-28 13:00 +0100
Message-ID<sTl3I-7Id-31@gated-at.bofh.it>
In reply to#1547617

[Multipart message — attachments visible in raw view] — view raw

Hi,

Alan Stern <stern@rowland.harvard.edu> writes:
>> > Index: usb-4.x/drivers/usb/gadget/legacy/inode.c
>> > ===================================================================
>> > --- usb-4.x.orig/drivers/usb/gadget/legacy/inode.c
>> > +++ usb-4.x/drivers/usb/gadget/legacy/inode.c
>> > @@ -1126,7 +1126,7 @@ ep0_write (struct file *fd, const char _
>> >  	/* data and/or status stage for control request */
>> >  	} else if (dev->state == STATE_DEV_SETUP) {
>> >  
>> > -		/* IN DATA+STATUS caller makes len <= wLength */
>> > +		len = min(len, (size_t) dev->setup_wLength);
>> >  		if (dev->setup_in) {
>> >  			retval = setup_req (dev->gadget->ep0, dev->req, len);
>> >  			if (retval == 0) {
>> >
>> 
>> I already have a patch from Greg for this. See [1]
>> 
>> [1] https://git.kernel.org/cgit/linux/kernel/git/balbi/usb.git/commit/?id=230bc0cb8ff222d9f0fbbd93a80393140b39481f
>
> The two patches fix different problems.  My patch goes on the pathway
> where dev->state > STATE_DEV_OPENED in dev_config(), and Greg's patch
> handles the case where it is <=.

Okay, here's what I have so far in my testing/fixes:

$ git --no-pager shortlog testing/fixes ^linus/master
Alan Stern (5):
      USB: dummy-hcd: fix bug in stop_activity (handle ep0)
      USB: gadgetfs: fix unbounded memory allocation bug
      USB: gadgetfs: fix use-after-free bug
      USB: gadgetfs: fix checks of wTotalLength in config descriptors
      USB: gadgetfs: remove unnecessary assignment

Baolin Wang (1):
      usb: gadget: f_fs: Fix possibe deadlock

Felipe Balbi (4):
      usb: dwc3: ep0: add dwc3_ep0_prepare_one_trb()
      usb: dwc3: ep0: explicitly call dwc3_ep0_prepare_one_trb()
      usb: dwc3: gadget: always unmap EP0 requests
      usb: dwc3: core: avoid Overflow events

Greg Kroah-Hartman (1):
      usb: gadgetfs: restrict upper bound on device configuration size

Grygorii Strashko (1):
      usb: dwc3: omap: fix race of pm runtime with irq handler in probe

Hans de Goede (1):
      usb: dwc3: pci: Fix dr_mode misspelling

Heikki Krogerus (1):
      usb: dwc3: pci: add Intel Gemini Lake PCI ID

Janusz Dziedzic (1):
      usb: dwc3: skip interrupt when ep disabled

John Youn (1):
      usb: dwc3: pci: Add "linux,sysdev_is_parent" property

Krzysztof Opasiak (1):
      usb: gadget: composite: Test get_alt() presence instead of set_alt()

Marek Szyprowski (1):
      usb: dwc2: fix flags for DMA descriptor allocation in dwc2_hsotg_ep_enable

Stefan Wahren (4):
      usb: dwc2: Do not set host parameter in peripheral mode
      usb: dwc2: fix dwc2_get_device_property for u8 and u16
      usb: dwc2: fix default value for DMA support
      usb: dwc2: gadget: fix default value for gadget-dma-desc

Vincent Pelletier (2):
      usb: gadget: f_fs: Document eventfd effect on descriptor format.
      usb: gadget: f_fs: Fix ExtCompat descriptor validation


-- 
balbi

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