From e2d4a80f93fcfaf72e2e20daf6a28e39c3b90677 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Linus=20L=C3=BCssing?= Date: Fri, 22 May 2020 19:04:13 +0200 Subject: [PATCH 1/3] mac80211: mesh: fix discovery timer re-arming issue / crash MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On a non-forwarding 802.11s link between two fairly busy neighboring nodes (iperf with -P 16 at ~850MBit/s TCP; 1733.3 MBit/s VHT-MCS 9 80MHz short GI VHT-NSS 4), so with frequent PREQ retries, usually after around 30-40 seconds the following crash would occur: [ 1110.822428] Unable to handle kernel read from unreadable memory at virtual address 00000000 [ 1110.830786] Mem abort info: [ 1110.833573] Exception class = IABT (current EL), IL = 32 bits [ 1110.839494] SET = 0, FnV = 0 [ 1110.842546] EA = 0, S1PTW = 0 [ 1110.845678] user pgtable: 4k pages, 48-bit VAs, pgd = ffff800076386000 [ 1110.852204] [0000000000000000] *pgd=00000000f6322003, *pud=00000000f62de003, *pmd=0000000000000000 [ 1110.861167] Internal error: Oops: 86000004 [#1] PREEMPT SMP [ 1110.866730] Modules linked in: pppoe ppp_async batman_adv ath10k_pci ath10k_core ath pppox ppp_generic nf_conntrack_ipv6 mac80211 iptable_nat ipt_REJECT ipt_MASQUERADE cfg80211 xt_time xt_tcpudp xt_state xt_nat xt_multiport xt_mark xt_mac xt_limit xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_FLOWOFFLOAD slhc nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 nf_nat_ipv4 nf_nat nf_log_ipv4 nf_flow_table_hw nf_flow_table nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtcache nf_conntrack iptable_mangle iptable_filter ip_tables crc_ccitt compat nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables nf_reject_ipv6 usb_storage xhci_plat_hcd xhci_pci xhci_hcd dwc3 usbcore usb_common [ 1110.932190] Process swapper/3 (pid: 0, stack limit = 0xffff0000090c8000) [ 1110.938884] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.14.162 #0 [ 1110.944965] Hardware name: LS1043A RGW Board (DT) [ 1110.949658] task: ffff8000787a81c0 task.stack: ffff0000090c8000 [ 1110.955568] PC is at 0x0 [ 1110.958097] LR is at call_timer_fn.isra.27+0x24/0x78 [ 1110.963055] pc : [<0000000000000000>] lr : [] pstate: 00400145 [ 1110.970440] sp : ffff00000801be10 [ 1110.973744] x29: ffff00000801be10 x28: ffff000008bf7018 [ 1110.979047] x27: ffff000008bf87c8 x26: ffff000008c160c0 [ 1110.984352] x25: 0000000000000000 x24: 0000000000000000 [ 1110.989657] x23: dead000000000200 x22: 0000000000000000 [ 1110.994959] x21: 0000000000000000 x20: 0000000000000101 [ 1111.000262] x19: ffff8000787a81c0 x18: 0000000000000000 [ 1111.005565] x17: ffff0000089167b0 x16: 0000000000000058 [ 1111.010868] x15: ffff0000089167b0 x14: 0000000000000000 [ 1111.016172] x13: ffff000008916788 x12: 0000000000000040 [ 1111.021475] x11: ffff80007fda9af0 x10: 0000000000000001 [ 1111.026777] x9 : ffff00000801bea0 x8 : 0000000000000004 [ 1111.032080] x7 : 0000000000000000 x6 : ffff80007fda9aa8 [ 1111.037383] x5 : ffff00000801bea0 x4 : 0000000000000010 [ 1111.042685] x3 : ffff00000801be98 x2 : 0000000000000614 [ 1111.047988] x1 : 0000000000000000 x0 : 0000000000000000 [ 1111.053290] Call trace: [ 1111.055728] Exception stack(0xffff00000801bcd0 to 0xffff00000801be10) [ 1111.062158] bcc0: 0000000000000000 0000000000000000 [ 1111.069978] bce0: 0000000000000614 ffff00000801be98 0000000000000010 ffff00000801bea0 [ 1111.077798] bd00: ffff80007fda9aa8 0000000000000000 0000000000000004 ffff00000801bea0 [ 1111.085618] bd20: 0000000000000001 ffff80007fda9af0 0000000000000040 ffff000008916788 [ 1111.093437] bd40: 0000000000000000 ffff0000089167b0 0000000000000058 ffff0000089167b0 [ 1111.101256] bd60: 0000000000000000 ffff8000787a81c0 0000000000000101 0000000000000000 [ 1111.109075] bd80: 0000000000000000 dead000000000200 0000000000000000 0000000000000000 [ 1111.116895] bda0: ffff000008c160c0 ffff000008bf87c8 ffff000008bf7018 ffff00000801be10 [ 1111.124715] bdc0: ffff0000080ff29c ffff00000801be10 0000000000000000 0000000000400145 [ 1111.132534] bde0: ffff8000787a81c0 ffff00000801bde8 0000ffffffffffff 000001029eb19be8 [ 1111.140353] be00: ffff00000801be10 0000000000000000 [ 1111.145220] [< (null)>] (null) [ 1111.149917] [] run_timer_softirq+0x184/0x398 [ 1111.155741] [] __do_softirq+0x100/0x1fc [ 1111.161130] [] irq_exit+0x80/0xd8 [ 1111.166002] [] __handle_domain_irq+0x88/0xb0 [ 1111.171825] [] gic_handle_irq+0x68/0xb0 [ 1111.177213] Exception stack(0xffff0000090cbe30 to 0xffff0000090cbf70) [ 1111.183642] be20: 0000000000000020 0000000000000000 [ 1111.191461] be40: 0000000000000001 0000000000000000 00008000771af000 0000000000000000 [ 1111.199281] be60: ffff000008c95180 0000000000000000 ffff000008c19360 ffff0000090cbef0 [ 1111.207101] be80: 0000000000000810 0000000000000400 0000000000000098 ffff000000000000 [ 1111.214920] bea0: 0000000000000001 ffff0000089167b0 0000000000000000 ffff0000089167b0 [ 1111.222740] bec0: 0000000000000000 ffff000008c198e8 ffff000008bf7018 ffff000008c19000 [ 1111.230559] bee0: 0000000000000000 0000000000000000 ffff8000787a81c0 ffff000008018000 [ 1111.238380] bf00: ffff00000801c000 ffff00000913ba34 ffff8000787a81c0 ffff0000090cbf70 [ 1111.246199] bf20: ffff0000080857cc ffff0000090cbf70 ffff0000080857d0 0000000000400145 [ 1111.254020] bf40: ffff000008018000 ffff00000801c000 ffffffffffffffff ffff0000080fa574 [ 1111.261838] bf60: ffff0000090cbf70 ffff0000080857d0 [ 1111.266706] [] el1_irq+0xe8/0x18c [ 1111.271576] [] arch_cpu_idle+0x10/0x18 [ 1111.276880] [] do_idle+0xec/0x1b8 [ 1111.281748] [] cpu_startup_entry+0x20/0x28 [ 1111.287399] [] secondary_start_kernel+0x104/0x110 [ 1111.293662] Code: bad PC value [ 1111.296710] ---[ end trace 555b6ca4363c3edd ]--- [ 1111.301318] Kernel panic - not syncing: Fatal exception in interrupt [ 1111.307661] SMP: stopping secondary CPUs [ 1111.311574] Kernel Offset: disabled [ 1111.315053] CPU features: 0x0002000 [ 1111.318530] Memory Limit: none [ 1111.321575] Rebooting in 3 seconds.. With some added debug output / delays we were able to push the crash from the timer callback runner into the callback function and by that shedding some light on which object holding the timer gets corrupted: [ 401.720899] Unable to handle kernel read from unreadable memory at virtual address 00000868 [...] [ 402.335836] [] _raw_spin_lock_bh+0x14/0x48 [ 402.341548] [] mesh_path_timer+0x10c/0x248 [mac80211] [ 402.348154] [] call_timer_fn.isra.27+0x24/0x78 [ 402.354150] [] run_timer_softirq+0x184/0x398 [ 402.359974] [] __do_softirq+0x100/0x1fc [ 402.365362] [] irq_exit+0x80/0xd8 [ 402.370231] [] __handle_domain_irq+0x88/0xb0 [ 402.376053] [] gic_handle_irq+0x68/0xb0 The issue happens due to the following sequence of events: 1) mesh_path_start_discovery(): -> spin_unlock_bh(&mpath->state_lock) before mesh_path_sel_frame_tx() 2) mesh_path_free_rcu() -> del_timer_sync(&mpath->timer) [...] -> kfree_rcu(mpath) 3) mesh_path_start_discovery(): -> mod_timer(&mpath->timer, ...) [...] -> rcu_read_unlock() 4) mesh_path_free_rcu()'s kfree_rcu(): -> kfree(mpath) 5) mesh_path_timer() starts after timeout, using freed mpath object So a use-after-free issue due to a timer re-arming bug caused by an early spin-unlocking. This patch fixes this issue by re-checking if mpath is about to be free'd and if so bails out of re-arming the timer. Cc: stable@vger.kernel.org Fixes: 050ac52cbe1f ("mac80211: code for on-demand Hybrid Wireless Mesh Protocol") Cc: Simon Wunderlich Signed-off-by: Linus Lüssing Link: https://lore.kernel.org/r/20200522170413.14973-1-linus.luessing@c0d3.blue Signed-off-by: Johannes Berg --- net/mac80211/mesh_hwmp.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c index 38a0383dfbcf..aa5150929996 100644 --- a/net/mac80211/mesh_hwmp.c +++ b/net/mac80211/mesh_hwmp.c @@ -1103,7 +1103,14 @@ void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata) mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr, ifmsh->sn, target_flags, mpath->dst, mpath->sn, da, 0, ttl, lifetime, 0, ifmsh->preq_id++, sdata); + + spin_lock_bh(&mpath->state_lock); + if (mpath->flags & MESH_PATH_DELETED) { + spin_unlock_bh(&mpath->state_lock); + goto enddiscovery; + } mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout); + spin_unlock_bh(&mpath->state_lock); enddiscovery: rcu_read_unlock(); From d031781bdabe1027858a3220f868866586bf6e7c Mon Sep 17 00:00:00 2001 From: Pradeep Kumar Chitrapu Date: Wed, 6 May 2020 03:24:30 -0700 Subject: [PATCH 2/3] ieee80211: Fix incorrect mask for default PE duration Fixes bitmask for HE opration's default PE duration. Fixes: daa5b83513a7 ("mac80211: update HE operation fields to D3.0") Signed-off-by: Pradeep Kumar Chitrapu Link: https://lore.kernel.org/r/20200506102430.5153-1-pradeepc@codeaurora.org Signed-off-by: Johannes Berg --- include/linux/ieee80211.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h index 16268ef1cbcc..5d3e48d02033 100644 --- a/include/linux/ieee80211.h +++ b/include/linux/ieee80211.h @@ -2047,7 +2047,7 @@ ieee80211_he_ppe_size(u8 ppe_thres_hdr, const u8 *phy_cap_info) } /* HE Operation defines */ -#define IEEE80211_HE_OPERATION_DFLT_PE_DURATION_MASK 0x00000003 +#define IEEE80211_HE_OPERATION_DFLT_PE_DURATION_MASK 0x00000007 #define IEEE80211_HE_OPERATION_TWT_REQUIRED 0x00000008 #define IEEE80211_HE_OPERATION_RTS_THRESHOLD_MASK 0x00003ff0 #define IEEE80211_HE_OPERATION_RTS_THRESHOLD_OFFSET 4 From 0bbab5f0301587cad4e923ccc49bb910db86162c Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 25 May 2020 11:38:17 +0200 Subject: [PATCH 3/3] cfg80211: fix debugfs rename crash Removing the "if (IS_ERR(dir)) dir = NULL;" check only works if we adjust the remaining code to not rely on it being NULL. Check IS_ERR_OR_NULL() before attempting to dereference it. I'm not actually entirely sure this fixes the syzbot crash as the kernel config indicates that they do have DEBUG_FS in the kernel, but this is what I found when looking there. Cc: stable@vger.kernel.org Fixes: d82574a8e5a4 ("cfg80211: no need to check return value of debugfs_create functions") Reported-by: syzbot+fd5332e429401bf42d18@syzkaller.appspotmail.com Reviewed-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20200525113816.fc4da3ec3d4b.Ica63a110679819eaa9fb3bc1b7437d96b1fd187d@changeid Signed-off-by: Johannes Berg --- net/wireless/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/wireless/core.c b/net/wireless/core.c index 341402b4f178..ce024440fa51 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -142,7 +142,7 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev, if (result) return result; - if (rdev->wiphy.debugfsdir) + if (!IS_ERR_OR_NULL(rdev->wiphy.debugfsdir)) debugfs_rename(rdev->wiphy.debugfsdir->d_parent, rdev->wiphy.debugfsdir, rdev->wiphy.debugfsdir->d_parent, newname);