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 A7DE8443AB7 for ; Wed, 26 Aug 2026 14:37:39 +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=1787755060; cv=none; b=nagQsRKb6HbTLc5QhQZaJcPAXuopn/SCQXHrVTtBrGMKzQuYIn6VjyzvXrVpz0dJEEdfSilh6uR9BqhdNo7rTAVViLMGUTyO9K/uNRo3qOBkvaVvPC32iHKytKxGiJCTOPyETpUdIrIe5kItx6u5TviANOwCKNDC0mF1QK6IK68= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787755060; c=relaxed/simple; bh=9phS+koMRL4yKLuTPurqZVDKz4vg4IImY+HCRO1sBUA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KgPvcIDVga1xk5Y2GcG+IErLiN84rg5SCjY4tft/LVzWE3e7yJY+KTpbtHkhN+Ja6A0TyUaJ4z/SzmT5BrbRv8lROEJkX0Qbcm9KB+mQ9JVvyDXFJt13ewXZqrhThAFPkFvc62c3y6LeDbxzgW5Le2cJmix1UaYpLtB84FLuJP8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=v86NfpxM; 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="v86NfpxM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDFC41F000E9; Wed, 26 Aug 2026 14:37:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787755059; bh=4wNu/Dq3luC3ACYNGzWBBLR5vnk/LQUJFtTuKTHb0uM=; h=From:To:Cc:Subject:Date:Reply-To; b=v86NfpxMyCnKgoVEW8+JqFCWLR0biXed1S8Xajvd1slC5Zv9cYs+3iGG8n9TvJ78x ewloH1CK8hIJyR5Sq01KGKHXQI00qpjbAOzIC+jxysTKCWBFcPIbZ++5OH70y7bfL0 B2Dv16bT/yfU/HUfhC789MVz5Xx1r5Tmp3E2xVFM= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74748: netfilter: ipset: fix refcount race between list:set GC and swap Date: Wed, 26 Aug 2026 16:37:08 +0200 Message-ID: <2026082659-CVE-2026-74748-e77a@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4611; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=y8OeZEvaBupzNeC3jEOZ97PpYO5C5Oqa24HqrxJPDPo=; b=owGbwMvMwCRo6H6F97bub03G02pJDFl9v7jLXppvT+LrPpK+5l+hu+zd24UXZ+f9lLuiZr5hz zbXmxMedMSyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBEasMZ5qlNU967LOol9+uk GbsXT42Nc9FaJskwz2LO2sXfbBsvhNf9jl3RF/xd+2NgBgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: fix refcount race between list:set GC and swap __ip_set_put_byindex() resolved the index to a set pointer under RCU, then took ip_set_ref_lock in __ip_set_put() to decrement set->ref. ip_set_swap() holds that same lock while swapping both the ip_set_list slots and the two sets' ref counters, so it can interleave between the dereference and the lock acquisition, leaving the caller to decrement a set whose reference already moved to the other index and hit BUG_ON(set->ref == 0). list_set_gc() reaches this from timer softirq, which the nfnl mutex does not serialize against swap: an expiring list:set member calls list_set_del() -> ip_set_put_byindex() while IPSET_CMD_SWAP runs on the referenced sets. Resolve the index and decrement under ip_set_ref_lock, as ip_set_swap() already does, keeping the refcount tied to the index rather than to a stale set pointer. kernel BUG at net/netfilter/ipset/ip_set_core.c:685! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ip_set_put_byindex (net/netfilter/ipset/ip_set_core.c:870) Call Trace: list_set_del (net/netfilter/ipset/ip_set_list_set.c:159) set_cleanup_entries (net/netfilter/ipset/ip_set_list_set.c:181) list_set_gc (net/netfilter/ipset/ip_set_list_set.c:578) call_timer_fn (kernel/time/timer.c:1748) __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2374) run_timer_softirq (kernel/time/timer.c:2405) Kernel panic - not syncing: Fatal exception in interrupt The Linux kernel CVE team has assigned CVE-2026-74748 to this issue. Affected and fixed versions =========================== Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 5.10.266 with commit 97a01de0c6321b7210d30d0a4d60f10f561097c7 Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 5.15.217 with commit c21afc7c216a4d257a4f3f300e0791890bc846b9 Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 6.1.184 with commit b0aab9dd1a348b99d75ff52765719d0cc2050630 Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 6.6.153 with commit b891e7a6bb06e0f6560e5932665ac660acd12225 Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 6.12.105 with commit 20cb13a523f0a05cb2d0a7d72abae687683712e0 Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 6.18.46 with commit cb20da33839f28f590c99f16bafaa6151451c0e8 Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 7.1.10 with commit 24ffcb1e1688c55fd2a505f064295cd28eac546d Issue introduced in 3.8 with commit 9076aea76538556224e7d73ab718f8841330818a and fixed in 7.2 with commit 0c88868271653537ed443272dd8e7d13634d214b Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-74748 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: net/netfilter/ipset/ip_set_core.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/97a01de0c6321b7210d30d0a4d60f10f561097c7 https://git.kernel.org/stable/c/c21afc7c216a4d257a4f3f300e0791890bc846b9 https://git.kernel.org/stable/c/b0aab9dd1a348b99d75ff52765719d0cc2050630 https://git.kernel.org/stable/c/b891e7a6bb06e0f6560e5932665ac660acd12225 https://git.kernel.org/stable/c/20cb13a523f0a05cb2d0a7d72abae687683712e0 https://git.kernel.org/stable/c/cb20da33839f28f590c99f16bafaa6151451c0e8 https://git.kernel.org/stable/c/24ffcb1e1688c55fd2a505f064295cd28eac546d https://git.kernel.org/stable/c/0c88868271653537ed443272dd8e7d13634d214b