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(unknown [36.110.52.3]) by APP-03 (Coremail) with SMTP id rQCowACXe+If2RZqs9eNEg--.14634S2; Wed, 27 May 2026 19:44:31 +0800 (CST) From: Jiakai Xu To: linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org Cc: Johannes Berg , Mathias Kretschmer , Simon Wunderlich , Jiakai Xu Subject: [PATCH] mac80211: suppress false WARNING when rate_mask is empty in __rate_control_send_low Date: Wed, 27 May 2026 11:44:30 +0000 Message-Id: <20260527114430.3682878-1-xujiakai24@mails.ucas.ac.cn> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: rQCowACXe+If2RZqs9eNEg--.14634S2 X-Coremail-Antispam: 1UD129KBjvJXoW3Ar43XF43Kr17ZFyUAr4rAFb_yoW3ur17pr y0grnrCF48Xan8AFW8Jw18JrW3XF47A3W3J397JryfJa43Cr1DXrnrKry8tr4UtrW7AF4x KF1qywsYyr9FyaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvC14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2vYz4IE04k24VAvwVAKI4IrM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI 64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVW8JVWxJw Am72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAG YxC7MxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r 1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CE b7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0x vE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAI cVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2Kf nxnUUI43ZEXa7VUjQeoUUUUUU== X-CM-SenderInfo: 50xmxthndljko6pdxz3voxutnvoduhdfq/ When the beacon generation path calls __rate_control_send_low() with a zero rate_mask (rc_rateidx_mask[band] =3D=3D 0), the loop skips all rates and triggers a WARN_ONCE even though there is no actual problem: the rate index defaults to 0, and the caller (rate_control_send_low) subsequently corrects it via rc_send_low_basicrate() using basic_rates. This scenario occurs when a user sets a per-band bitrate mask via NL80211_CMD_SET_TX_BITRATE_MASK on a band different from the one where a beacon is later sent (e.g., after CSA). Fix by wrapping the WARN_ONCE in a check for rate_mask !=3D 0. When rate_mask is 0, no rates were filtered out =E2=80=94 just the max rate index was reached because no specific mask was applied =E2=80=94 so the warning is a false positive. Fixes: 2103dec14792 ("mac80211: select and adjust bitrates according to cha= nnel mode") Signed-off-by: Jiakai Xu --- net/mac80211/rate.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c index ba1a3aa3f5d4..5cafc5043f19 100644 --- a/net/mac80211/rate.c +++ b/net/mac80211/rate.c @@ -396,12 +396,13 @@ static void __rate_control_send_low(struct ieee80211_= hw *hw, info->control.rates[0].idx =3D i; break; } - WARN_ONCE(i =3D=3D sband->n_bitrates, - "no supported rates for sta %pM (0x%x, band %d) in rate_mask 0x%x with= flags 0x%x\n", - sta ? sta->addr : NULL, - sta ? sta->deflink.supp_rates[sband->band] : -1, - sband->band, - rate_mask, rate_flags); + if (rate_mask) + WARN_ONCE(i =3D=3D sband->n_bitrates, + "no supported rates for sta %pM (0x%x, band %d) in rate_mask 0x%x wit= h flags 0x%x\n", + sta ? sta->addr : NULL, + sta ? sta->deflink.supp_rates[sband->band] : -1, + sband->band, + rate_mask, rate_flags); =20 info->control.rates[0].count =3D (info->flags & IEEE80211_TX_CTL_NO_ACK) ? --=20 2.34.1 Found by fuzzing. Here is the report: ------------[ cut here ]------------ no supported rates for sta (null) (0xffffffff, band 0) in rate_mask 0x0 wit= h flags 0x0 WARNING: net/mac80211/rate.c:406 at __rate_control_send_low+0x20f/0x260 hom= e/zzzrrll/tmp/linux-7.0.10/net/mac80211/rate.c:401, CPU#0: swapper/0/0 Modules linked in: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G L 7.0.10 #= 2 PREEMPT(full)=20 Tainted: [L]=3DSOFTLOCKUP Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/= 2014 RIP: 0010:__rate_control_send_low+0x249/0x260 home/zzzrrll/tmp/linux-7.0.10= /net/mac80211/rate.c:401 Code: 10 41 8b 94 85 d4 00 00 00 eb 0e e8 e1 18 14 fc ba ff ff ff ff 48 8b = 0c 24 8b 49 10 4c 89 f7 4c 89 ee 44 8b 44 24 0c 41 89 e9 <67> 48 0f b9 3a e= 9 40 ff ff ff 66 66 66 66 2e 0f 1f 84 00 00 00 00 RSP: 0018:ffa0000000003a78 EFLAGS: 00010246 RAX: ffffffff855306ef RBX: 000000000000000c RCX: 0000000000000000 RDX: 00000000ffffffff RSI: 0000000000000000 RDI: ffffffff877d9fa0 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: ffffffff8702d780 R12: 0000000000000800 R13: 0000000000000000 R14: ffffffff877d9fa0 R15: ff11000018fba128 FS: 0000000000000000(0000) GS:ff110000f40c5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32f23ffc CR3: 0000000023fe1000 CR4: 0000000000751ef0 PKRU: 55555554 Call Trace: rate_control_send_low+0xae/0x240 home/zzzrrll/tmp/linux-7.0.10/net/mac8021= 1/rate.c:429 rate_control_get_rate+0x6f/0x1c0 home/zzzrrll/tmp/linux-7.0.10/net/mac8021= 1/rate.c:943 ieee80211_beacon_get_finish+0x1f2/0x230 home/zzzrrll/tmp/linux-7.0.10/net/= mac80211/tx.c:5367 __ieee80211_beacon_get_ap home/zzzrrll/tmp/linux-7.0.10/net/mac80211/tx.c:= 5470 [inline] ieee80211_beacon_get_ap+0xb94/0xc40 home/zzzrrll/tmp/linux-7.0.10/net/mac8= 0211/tx.c:5532 __ieee80211_beacon_get+0x938/0xa80 home/zzzrrll/tmp/linux-7.0.10/net/mac80= 211/tx.c:5638 ieee80211_beacon_get_tim+0x60/0x150 home/zzzrrll/tmp/linux-7.0.10/net/mac8= 0211/tx.c:5780 ieee80211_beacon_get home/zzzrrll/tmp/linux-7.0.10/include/net/mac80211.h:= 5720 [inline] mac80211_hwsim_beacon_tx+0x1bc/0x350 home/zzzrrll/tmp/linux-7.0.10/drivers= /net/wireless/virtual/mac80211_hwsim.c:2361 __iterate_interfaces+0x1af/0x290 home/zzzrrll/tmp/linux-7.0.10/net/mac8021= 1/util.c:760 ieee80211_iterate_active_interfaces_atomic+0x32/0x40 home/zzzrrll/tmp/linu= x-7.0.10/net/mac80211/util.c:796 mac80211_hwsim_beacon+0x63/0xd0 home/zzzrrll/tmp/linux-7.0.10/drivers/net/= wireless/virtual/mac80211_hwsim.c:2395 __run_hrtimer home/zzzrrll/tmp/linux-7.0.10/kernel/time/hrtimer.c:1790 [in= line] __hrtimer_run_queues+0x168/0x3b0 home/zzzrrll/tmp/linux-7.0.10/kernel/time= /hrtimer.c:1854 hrtimer_run_softirq+0xa3/0x1f0 home/zzzrrll/tmp/linux-7.0.10/kernel/time/h= rtimer.c:1871 handle_softirqs+0xdc/0x2d0 home/zzzrrll/tmp/linux-7.0.10/kernel/softirq.c:= 622 __do_softirq home/zzzrrll/tmp/linux-7.0.10/kernel/softirq.c:656 [inline] invoke_softirq home/zzzrrll/tmp/linux-7.0.10/kernel/softirq.c:496 [inline] __irq_exit_rcu+0x44/0xd0 home/zzzrrll/tmp/linux-7.0.10/kernel/softirq.c:723 instr_sysvec_apic_timer_interrupt home/zzzrrll/tmp/linux-7.0.10/arch/x86/k= ernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x76/0x90 home/zzzrrll/tmp/linux-7.0.10/arch/x= 86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 home/zzzrrll/tmp/linux-7.0.10/ar= ch/x86/include/asm/idtentry.h:697 RIP: 0010:pv_native_safe_halt+0x13/0x20 home/zzzrrll/tmp/linux-7.0.10/arch/= x86/kernel/paravirt.c:63 Code: ee 27 83 fb cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 = f3 0f 1e fa eb 07 0f 00 2d a3 1c 15 00 f3 0f 1e fa fb f4 c3 27 83 fb c= c cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffffff87003e88 EFLAGS: 00000212 RAX: ff110000f40c5000 RBX: 0000000000000000 RCX: 4000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000002d5c79c RBP: 0000000000000000 R08: ffffffff81606126 R09: 0000000000000012 R10: 000001f47d45d440 R11: ffffffff813a87f0 R12: 0000000000000000 R13: ffffffff8994f020 R14: ffffffff8702d780 R15: 0000000000000000 arch_safe_halt home/zzzrrll/tmp/linux-7.0.10/arch/x86/kernel/process.c:766= [inline] default_idle+0x9/0x10 home/zzzrrll/tmp/linux-7.0.10/arch/x86/kernel/proces= s.c:767 default_idle_call+0x3c/0x60 home/zzzrrll/tmp/linux-7.0.10/kernel/sched/idl= e.c:122 cpuidle_idle_call home/zzzrrll/tmp/linux-7.0.10/kernel/sched/idle.c:199 [i= nline] do_idle+0x18f/0x2c0 home/zzzrrll/tmp/linux-7.0.10/kernel/sched/idle.c:352 cpu_startup_entry+0x25/0x30 home/zzzrrll/tmp/linux-7.0.10/kernel/sched/idl= e.c:451 rest_init+0xc0/0xc0 home/zzzrrll/tmp/linux-7.0.10/init/main.c:760 start_kernel+0x34f/0x380 home/zzzrrll/tmp/linux-7.0.10/init/main.c:1209 x86_64_start_reservations+0x24/0x30 home/zzzrrll/tmp/linux-7.0.10/arch/x86= /kernel/head64.c:310 x86_64_start_kernel+0x109/0x110 home/zzzrrll/tmp/linux-7.0.10/arch/x86/ker= nel/head64.c:291 common_startup_64+0x13e/0x147 ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 41 8b 94 85 d4 00 00 mov 0xd4(%r13,%rax,4),%edx 7: 00 8: eb 0e jmp 0x18 a: e8 e1 18 14 fc call 0xfc1418f0 f: ba ff ff ff ff mov $0xffffffff,%edx 14: 48 8b 0c 24 mov (%rsp),%rcx 18: 8b 49 10 mov 0x10(%rcx),%ecx 1b: 4c 89 f7 mov %r14,%rdi 1e: 4c 89 ee mov %r13,%rsi 21: 44 8b 44 24 0c mov 0xc(%rsp),%r8d 26: 41 89 e9 mov %ebp,%r9d * 29: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2e: e9 40 ff ff ff jmp 0xffffff73 33: 66 data16 34: 66 data16 35: 66 data16 36: 66 data16 37: 2e cs 38: 0f .byte 0xf 39: 1f (bad) 3a: 84 00 test %al,(%rax) 3c: 00 00 add %al,(%rax)