Minsuk Kang <linuxlovemin@xxxxxxxxxxxx> wrote: > This patch fixes a slab-out-of-bounds read in brcmfmac that occurs in > cfg80211_find_elem_match() called from brcmf_inform_single_bss() when > the offset and length values of information elements provided by the > device exceed the boundary of the escan buffer that contains information > elements. The patch adds a check that makes the function return -EINVAL > if that is the case. Note that the negative return is handled by the > caller, brcmf_inform_bss(). > > Found by a modified version of syzkaller. > > ================================================================== > BUG: KASAN: slab-out-of-bounds in cfg80211_find_elem_match+0x164/0x180 > Read of size 1 at addr ffff888018f0fde9 by task kworker/0:2/1896 > > CPU: 0 PID: 1896 Comm: kworker/0:2 Tainted: G O 5.14.0+ #139 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 > Workqueue: events brcmf_fweh_event_worker > Call Trace: > dump_stack_lvl+0x8e/0xd1 > print_address_description.constprop.0.cold+0x93/0x334 > ? cfg80211_find_elem_match+0x164/0x180 > kasan_report.cold+0x79/0xd5 > ? cfg80211_find_elem_match+0x164/0x180 > cfg80211_find_elem_match+0x164/0x180 > cfg80211_get_bss_channel+0x69/0x320 > cfg80211_inform_single_bss_data+0x1a6/0x1060 > ? cfg80211_bss_update+0x1e20/0x1e20 > ? rcu_read_lock_sched_held+0xa1/0xd0 > ? rcu_read_lock_bh_held+0xb0/0xb0 > ? find_held_lock+0x2d/0x110 > ? cfg80211_inform_bss_data+0xcb/0x160 > cfg80211_inform_bss_data+0xcb/0x160 > ? cfg80211_parse_mbssid_data+0x1540/0x1540 > ? kvm_clock_get_cycles+0x14/0x20 > ? ktime_get_with_offset+0x2b9/0x450 > brcmf_inform_single_bss+0x36d/0x4d0 > ? brcmf_notify_mic_status+0xb0/0xb0 > ? __lock_acquire+0x181f/0x5790 > ? brcmf_p2p_cancel_remain_on_channel+0x30/0x30 > brcmf_inform_bss+0x131/0x210 > brcmf_cfg80211_escan_handler+0x779/0xd20 > ? rcu_read_lock_bh_held+0xb0/0xb0 > ? lock_acquire+0x19d/0x4e0 > ? find_held_lock+0x2d/0x110 > ? brcmf_cfg80211_escan_timeout_worker+0x60/0x60 > ? brcmf_fweh_event_worker+0x249/0xc00 > ? mark_held_locks+0x9f/0xe0 > ? lockdep_hardirqs_on_prepare+0x3e0/0x3e0 > ? brcmf_cfg80211_escan_timeout_worker+0x60/0x60 > brcmf_fweh_call_event_handler.isra.0+0x90/0x100 > brcmf_fweh_event_worker+0x117/0xc00 > ? brcmf_fweh_call_event_handler.isra.0+0x100/0x100 > ? rcu_read_lock_sched_held+0xa1/0xd0 > ? rcu_read_lock_bh_held+0xb0/0xb0 > ? lockdep_hardirqs_on_prepare+0x273/0x3e0 > process_one_work+0x92b/0x1460 > ? pwq_dec_nr_in_flight+0x330/0x330 > ? rwlock_bug.part.0+0x90/0x90 > worker_thread+0x95/0xe00 > ? __kthread_parkme+0x115/0x1e0 > ? process_one_work+0x1460/0x1460 > kthread+0x3a1/0x480 > ? set_kthread_struct+0x120/0x120 > ret_from_fork+0x1f/0x30 > > The buggy address belongs to the page: > page:ffffea000063c000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x18f00 > head:ffffea000063c000 order:4 compound_mapcount:0 compound_pincount:0 > flags: 0x100000000010000(head|node=0|zone=1) > raw: 0100000000010000 0000000000000000 dead000000000122 0000000000000000 > raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 4, migratetype Unmovable, gfp_mask 0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), pid 1896, ts 44510886600, free_ts 0 > prep_new_page+0x1aa/0x240 > get_page_from_freelist+0x159a/0x27c0 > __alloc_pages+0x2da/0x6a0 > alloc_pages+0xec/0x1e0 > kmalloc_order+0x39/0xf0 > kmalloc_order_trace+0x19/0x120 > brcmf_cfg80211_attach+0x5c9/0x3fd0 > brcmf_attach+0x389/0xd40 > brcmf_usb_probe+0x12de/0x1690 > usb_probe_interface+0x2aa/0x760 > really_probe+0x205/0xb70 > __driver_probe_device+0x311/0x4b0 > driver_probe_device+0x4e/0x150 > __device_attach_driver+0x1cc/0x2a0 > bus_for_each_drv+0x156/0x1d0 > __device_attach+0x23f/0x3a0 > page_owner free stack trace missing > > Memory state around the buggy address: > ffff888018f0fc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff888018f0fd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff888018f0fd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 fe fe fe > ^ > ffff888018f0fe00: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe > ffff888018f0fe80: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe > ================================================================== > > Reported-by: Dokyung Song <dokyungs@xxxxxxxxxxxx> > Reported-by: Jisoo Jang <jisoo.jang@xxxxxxxxxxxx> > Reported-by: Minsuk Kang <linuxlovemin@xxxxxxxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> > Signed-off-by: Minsuk Kang <linuxlovemin@xxxxxxxxxxxx> Arend, can you take a look at this? I don't dare to take it unless you have checked it. -- https://patchwork.kernel.org/project/linux-wireless/patch/20221116145821.544266-1-linuxlovemin@xxxxxxxxxxxx/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
