Re: [PATCH 4.14 230/338] wifi: brcmfmac: Fix potential shift-out-of-bounds in brcmf_fw_alloc_request()

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On Wed, Jan 18, 2023 at 09:21:05AM -0700, Nathan Chancellor wrote:
> On Mon, Jan 16, 2023 at 04:51:43PM +0100, Greg Kroah-Hartman wrote:
> > From: Minsuk Kang <linuxlovemin@xxxxxxxxxxxx>
> > 
> > [ Upstream commit 81d17f6f3331f03c8eafdacea68ab773426c1e3c ]
> > 
> > This patch fixes a shift-out-of-bounds in brcmfmac that occurs in
> > BIT(chiprev) when a 'chiprev' provided by the device is too large.
> > It should also not be equal to or greater than BITS_PER_TYPE(u32)
> > as we do bitwise AND with a u32 variable and BIT(chiprev). The patch
> > adds a check that makes the function return NULL if that is the case.
> > Note that the NULL case is later handled by the bus-specific caller,
> > brcmf_usb_probe_cb() or brcmf_usb_reset_resume(), for example.
> > 
> > Found by a modified version of syzkaller.
> > 
> > UBSAN: shift-out-of-bounds in drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> > shift exponent 151055786 is too large for 64-bit type 'long unsigned int'
> > CPU: 0 PID: 1885 Comm: kworker/0:2 Tainted: G           O      5.14.0+ #132
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
> > Workqueue: usb_hub_wq hub_event
> > Call Trace:
> >  dump_stack_lvl+0x57/0x7d
> >  ubsan_epilogue+0x5/0x40
> >  __ubsan_handle_shift_out_of_bounds.cold+0x53/0xdb
> >  ? lock_chain_count+0x20/0x20
> >  brcmf_fw_alloc_request.cold+0x19/0x3ea
> >  ? brcmf_fw_get_firmwares+0x250/0x250
> >  ? brcmf_usb_ioctl_resp_wait+0x1a7/0x1f0
> >  brcmf_usb_get_fwname+0x114/0x1a0
> >  ? brcmf_usb_reset_resume+0x120/0x120
> >  ? number+0x6c4/0x9a0
> >  brcmf_c_process_clm_blob+0x168/0x590
> >  ? put_dec+0x90/0x90
> >  ? enable_ptr_key_workfn+0x20/0x20
> >  ? brcmf_common_pd_remove+0x50/0x50
> >  ? rcu_read_lock_sched_held+0xa1/0xd0
> >  brcmf_c_preinit_dcmds+0x673/0xc40
> >  ? brcmf_c_set_joinpref_default+0x100/0x100
> >  ? rcu_read_lock_sched_held+0xa1/0xd0
> >  ? rcu_read_lock_bh_held+0xb0/0xb0
> >  ? lock_acquire+0x19d/0x4e0
> >  ? find_held_lock+0x2d/0x110
> >  ? brcmf_usb_deq+0x1cc/0x260
> >  ? mark_held_locks+0x9f/0xe0
> >  ? lockdep_hardirqs_on_prepare+0x273/0x3e0
> >  ? _raw_spin_unlock_irqrestore+0x47/0x50
> >  ? trace_hardirqs_on+0x1c/0x120
> >  ? brcmf_usb_deq+0x1a7/0x260
> >  ? brcmf_usb_rx_fill_all+0x5a/0xf0
> >  brcmf_attach+0x246/0xd40
> >  ? wiphy_new_nm+0x1476/0x1d50
> >  ? kmemdup+0x30/0x40
> >  brcmf_usb_probe+0x12de/0x1690
> >  ? brcmf_usbdev_qinit.constprop.0+0x470/0x470
> >  usb_probe_interface+0x25f/0x710
> >  really_probe+0x1be/0xa90
> >  __driver_probe_device+0x2ab/0x460
> >  ? usb_match_id.part.0+0x88/0xc0
> >  driver_probe_device+0x49/0x120
> >  __device_attach_driver+0x18a/0x250
> >  ? driver_allows_async_probing+0x120/0x120
> >  bus_for_each_drv+0x123/0x1a0
> >  ? bus_rescan_devices+0x20/0x20
> >  ? lockdep_hardirqs_on_prepare+0x273/0x3e0
> >  ? trace_hardirqs_on+0x1c/0x120
> >  __device_attach+0x207/0x330
> >  ? device_bind_driver+0xb0/0xb0
> >  ? kobject_uevent_env+0x230/0x12c0
> >  bus_probe_device+0x1a2/0x260
> >  device_add+0xa61/0x1ce0
> >  ? __mutex_unlock_slowpath+0xe7/0x660
> >  ? __fw_devlink_link_to_suppliers+0x550/0x550
> >  usb_set_configuration+0x984/0x1770
> >  ? kernfs_create_link+0x175/0x230
> >  usb_generic_driver_probe+0x69/0x90
> >  usb_probe_device+0x9c/0x220
> >  really_probe+0x1be/0xa90
> >  __driver_probe_device+0x2ab/0x460
> >  driver_probe_device+0x49/0x120
> >  __device_attach_driver+0x18a/0x250
> >  ? driver_allows_async_probing+0x120/0x120
> >  bus_for_each_drv+0x123/0x1a0
> >  ? bus_rescan_devices+0x20/0x20
> >  ? lockdep_hardirqs_on_prepare+0x273/0x3e0
> >  ? trace_hardirqs_on+0x1c/0x120
> >  __device_attach+0x207/0x330
> >  ? device_bind_driver+0xb0/0xb0
> >  ? kobject_uevent_env+0x230/0x12c0
> >  bus_probe_device+0x1a2/0x260
> >  device_add+0xa61/0x1ce0
> >  ? __fw_devlink_link_to_suppliers+0x550/0x550
> >  usb_new_device.cold+0x463/0xf66
> >  ? hub_disconnect+0x400/0x400
> >  ? _raw_spin_unlock_irq+0x24/0x30
> >  hub_event+0x10d5/0x3330
> >  ? hub_port_debounce+0x280/0x280
> >  ? __lock_acquire+0x1671/0x5790
> >  ? wq_calc_node_cpumask+0x170/0x2a0
> >  ? lock_release+0x640/0x640
> >  ? rcu_read_lock_sched_held+0xa1/0xd0
> >  ? rcu_read_lock_bh_held+0xb0/0xb0
> >  ? lockdep_hardirqs_on_prepare+0x273/0x3e0
> >  process_one_work+0x873/0x13e0
> >  ? lock_release+0x640/0x640
> >  ? pwq_dec_nr_in_flight+0x320/0x320
> >  ? rwlock_bug.part.0+0x90/0x90
> >  worker_thread+0x8b/0xd10
> >  ? __kthread_parkme+0xd9/0x1d0
> >  ? process_one_work+0x13e0/0x13e0
> >  kthread+0x379/0x450
> >  ? _raw_spin_unlock_irq+0x24/0x30
> >  ? set_kthread_struct+0x100/0x100
> >  ret_from_fork+0x1f/0x30
> > 
> > Reported-by: Dokyung Song <dokyungs@xxxxxxxxxxxx>
> > Reported-by: Jisoo Jang <jisoo.jang@xxxxxxxxxxxx>
> > Reported-by: Minsuk Kang <linuxlovemin@xxxxxxxxxxxx>
> > Signed-off-by: Minsuk Kang <linuxlovemin@xxxxxxxxxxxx>
> > Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxx>
> > Link: https://lore.kernel.org/r/20221024071329.504277-1-linuxlovemin@xxxxxxxxxxxx
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >  drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> > index 13c25798f39a..6d868b8b441a 100644
> > --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c
> > @@ -572,6 +572,11 @@ int brcmf_fw_map_chip_to_name(u32 chip, u32 chiprev,
> >  	u32 i;
> >  	char end;
> >  
> > +	if (chiprev >= BITS_PER_TYPE(u32)) {
> > +		brcmf_err("Invalid chip revision %u\n", chiprev);
> > +		return NULL;
> > +	}
> > +
> >  	for (i = 0; i < table_size; i++) {
> >  		if (mapping_table[i].chipid == chip &&
> >  		    mapping_table[i].revmask & BIT(chiprev))
> > -- 
> > 2.35.1
> 
> Clang points out that this backport is incorrect:
> 
>   drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c:577:10: error: incompatible pointer to integer conversion returning 'void *' from a function with result type 'int' [-Wint-conversion]
>                   return NULL;
>                          ^~~~
>   include/linux/stddef.h:8:14: note: expanded from macro 'NULL'
>   #define NULL ((void *)0)
>                ^~~~~~~~~~~
>   1 error generated.
> 
> That should probably be something like -EINVAL for 4.14 but I am not
> sure, hence just the report. This code path was reworked in commit
> 2baa3aaee27f ("brcmfmac: introduce brcmf_fw_alloc_request() function").
> Returning NULL would be treated as an error in the callers, which would
> require a negative return code here.

Good catch, I'll fix this up on Monday, thanks for reporting it!

greg k-h



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