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 68E6351C040; Wed, 30 Sep 2026 18:23:30 +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=1790792612; cv=none; b=hFSc4a0Q7bjcO0OxO9vbaDnF7LU+VmMRkv0hRjbkPJ65tCJfoikWNnCij2tVxNqtwJ9ndDvn/955sRkC0pK9snQ2jbCu1q1lods9LGYEsrEK9aP3zDiBaKBVNI6LX+2fBM/NwptcpSb3xLPyf1YZCLxx+I3D5nA5JGEL1Tki0IE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790792612; c=relaxed/simple; bh=9/NS1Q2TRcIQ44fVAJ3vGtCeEGSXIup4/xa48qjyDlg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I1AEHRNeuXXCq4fb7sfI4fw7VR7j+nc8cVn4TzbAtqBnZ6DSuoEf/Tm96UQKENrpI7X12fylxVwRp4tQKQSb7hKkuOH/3plopcAtUUX/xeltOwV3aL/S0vF6JZxWr2ZR0M4/SNGxKm7adHvpGpVj59ihq0tmXq/wJgfEfCs5JgY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HFIm66xo; 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="HFIm66xo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B60761F00899; Wed, 30 Sep 2026 18:23:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790792610; bh=spJPgcE4nd2h66C0PuFjDHAaVmCKAfDiga7y9PBbAyo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HFIm66xo3PtSOuSc4ifWcwlZu4gUc1tzLi1N3STjYYj+wFvJdJzj5ivMMKud8m5Lr zUMjlqzuz10iGVoZkYDvAbMnluurQzE2nrroTPZ96Y+7hSpGd6VjPfMsKsnISCijod 1RsxebULB8TPdx8q1DoXrCN+hPOQuWCoZaq+Chn4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Weiming Shi , Jakub Kicinski Subject: [PATCH 5.15 717/752] net/sched: reject IDR error pointers when deleting actions Date: Wed, 30 Sep 2026 17:29:47 +0200 Message-ID: <20260930152413.740007679@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weiming Shi commit c82b797abe668d0b668601a93ba2c0b071a63574 upstream. tcf_action_delete() drops the reference held by its lookup before calling tcf_idr_delete_index() with the saved action index. An unlocked classifier can remove that action and reserve the same IDR slot with ERR_PTR(-EBUSY) in between. tcf_idr_delete_index() only checks the lookup result for NULL. It therefore treats the reservation as a tc_action and dereferences tcfa_bindcnt. A hardware execution breakpoint was used to schedule the interleaving without changing the kernel source. KASAN reported this decoded trace: BUG: KASAN: null-ptr-deref in tca_action_gd+0x5b9/0x1010 Read of size 4 at addr 0000000000000010 by task poc/150 Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002 RIP: tca_action_gd+0x5c0/0x1010: arch_atomic_read at arch/x86/include/asm/atomic.h:23 raw_atomic_read at include/linux/atomic/atomic-arch-fallback.h:457 atomic_read at include/linux/atomic/atomic-instrumented.h:33 tcf_idr_delete_index at net/sched/act_api.c:766 tcf_action_delete at net/sched/act_api.c:1859 tcf_del_notify at net/sched/act_api.c:2014 tca_action_gd at net/sched/act_api.c:2064 R13: 0000000000000010 R15: fffffffffffffff0 Kernel panic - not syncing: Fatal exception R15 contains ERR_PTR(-EBUSY), and adding the tcfa_bindcnt offset produces the address in R13. With the guard applied, the same reproducer returned -ENOENT without a KASAN report or panic. Treat error pointers as absent and return -ENOENT. Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action") Cc: stable@vger.kernel.org Reported-by: Xiang Mei Signed-off-by: Weiming Shi Link: https://patch.msgid.link/20260914065123.4109709-2-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/sched/act_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -449,7 +449,7 @@ static int tcf_idr_delete_index(struct t mutex_lock(&idrinfo->lock); p = idr_find(&idrinfo->action_idr, index); - if (!p) { + if (IS_ERR_OR_NULL(p)) { mutex_unlock(&idrinfo->lock); return -ENOENT; }