From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E1DE2E1EFC; Sun, 7 Jun 2026 10:08:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780826928; cv=none; b=rb+9qOeY4VNKjnhdX2YMCimUAuYT9QTgITk0sJK/edxtD8IS8+ZXLPDhLa0uUkds5ewO4CwAjc6meM9Gg+8F/ew9dQprz75+Y3k3XyVou8d9gcYCxPaRcP54hKvtBMItp4fqOQJgZNihM9vVE2y9wkAjOlkAAaePOL+Gn4cucOY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780826928; c=relaxed/simple; bh=wvdDfP+0KvIeFSQ6j/6U2U0IyvusIdij/E901X79t9M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=L2MRudADK10TqXA2OoxUjrsIysDv7J1s+X61l5wCFxLQ4lnviZR5sI005cBt7VPXGGUbvFo6nN/Wc5Mu2cPqnHy5KPftONhFTj5vS0/J0LjjqadsS3X15wwVIwt2OvDOzH2TszdN5z0+b0vHq8pOwgVYe+FupSBRNuRHUvKgRac= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JbSP72uM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="JbSP72uM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96A751F00893; Sun, 7 Jun 2026 10:08:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780826927; bh=a75nooePKp4LNYsXiWymJZoGInLIZVHV3pT5VQCjVGQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JbSP72uM5hE94/LuwewqQm/O4vRmayPfP3qjWeQzzTRdTAHjFvScyNokTTYY6fg52 e9XKPCauEDDnyDJDsQCzDpNp/2eROXB5JQKSs1xgGyjNP4k6iQie4fkGP5CVlOL9tt 1eVXKU/n6inwcUvr8Zs+hwUOKXoagkhVAf5xbpEo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Victor Nogueria , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 007/307] net/sched: sch_sfb: Replace direct dequeue call with peek and qdisc_dequeue_peeked Date: Sun, 7 Jun 2026 11:56:44 +0200 Message-ID: <20260607095727.907948605@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260607095727.647295505@linuxfoundation.org> References: <20260607095727.647295505@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Victor Nogueria [ Upstream commit 1b9bc71153b01dbde8045b9edede4240f4f5520e ] When sfb has children (eg qfq qdisc) whose peek() callback is qdisc_peek_dequeued(), we could get a kernel panic. When the parent of such qdiscs (eg illustrated in patch #3 as tbf) wants to retrieve an skb from its child (sfb in this case), it will do the following: 1a. do a peek() - and when sensing there's an skb the child can offer, then - the child in this case(sfb) calls its child's (qfq) peek. qfq does the right thing and will return the gso_skb queue packet. Note: if there wasnt a gso_skb entry then qfq will store it there. 1b. invoke a dequeue() on the child (sfb). And herein lies the problem. - sfb will call the child's dequeue() which will essentially just try to grab something of qfq's queue. [ 127.594489][ T453] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 127.594741][ T453] CPU: 2 UID: 0 PID: 453 Comm: ping Not tainted 7.1.0-rc1-00035-gac961974495b-dirty #793 PREEMPT(full) [ 127.595059][ T453] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 127.595254][ T453] RIP: 0010:qfq_dequeue+0x35c/0x1650 [sch_qfq] [ 127.595461][ T453] Code: 00 fc ff df 80 3c 02 00 0f 85 17 0e 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 76 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b [ 127.596081][ T453] RSP: 0018:ffff88810e5af440 EFLAGS: 00010216 [ 127.596337][ T453] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 127.596623][ T453] RDX: 0000000000000009 RSI: 0000001880000000 RDI: ffff888104fd82b0 [ 127.596917][ T453] RBP: ffff888104fd8000 R08: ffff888104fd8280 R09: 1ffff110211893a3 [ 127.597165][ T453] R10: 1ffff110211893a6 R11: 1ffff110211893a7 R12: 0000001880000000 [ 127.597404][ T453] R13: ffff888104fd82b8 R14: 0000000000000048 R15: 0000000040000000 [ 127.597644][ T453] FS: 00007fc380cbfc40(0000) GS:ffff88816f2a8000(0000) knlGS:0000000000000000 [ 127.597956][ T453] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 127.598160][ T453] CR2: 00005610aa9890a8 CR3: 000000010369e000 CR4: 0000000000750ef0 [ 127.598390][ T453] PKRU: 55555554 [ 127.598509][ T453] Call Trace: [ 127.598629][ T453] [ 127.598718][ T453] ? mark_held_locks+0x40/0x70 [ 127.598890][ T453] ? srso_alias_return_thunk+0x5/0xfbef5 [ 127.599053][ T453] sfb_dequeue+0x88/0x4d0 [ 127.599174][ T453] ? ktime_get+0x137/0x230 [ 127.599328][ T453] ? srso_alias_return_thunk+0x5/0xfbef5 [ 127.599480][ T453] ? qdisc_peek_dequeued+0x7b/0x350 [sch_qfq] [ 127.599670][ T453] ? srso_alias_return_thunk+0x5/0xfbef5 [ 127.599831][ T453] tbf_dequeue+0x6b1/0x1098 [sch_tbf] [ 127.599988][ T453] __qdisc_run+0x169/0x1900 The right thing to do in #1b is to grab the skb off gso_skb queue. This patchset fixes that issue by changing #1b to use qdisc_dequeue_peeked() method instead. Fixes: e13e02a3c68d ("net_sched: SFB flow scheduler") Signed-off-by: Victor Nogueria Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260430152957.194015-3-jhs@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_sfb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c index c36725f0870d46..9a2edaf8352adc 100644 --- a/net/sched/sch_sfb.c +++ b/net/sched/sch_sfb.c @@ -439,7 +439,7 @@ static struct sk_buff *sfb_dequeue(struct Qdisc *sch) struct Qdisc *child = q->qdisc; struct sk_buff *skb; - skb = child->dequeue(q->qdisc); + skb = qdisc_dequeue_peeked(child); if (skb) { qdisc_bstats_update(sch, skb); -- 2.53.0