From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE6723B6BF5 for ; Sat, 1 Aug 2026 05:42:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785562975; cv=none; b=jENmgTf6chTtw5EtuNMpBroL0TevFgxg+TS3l4cwuayK8VkhHB6L7zjKxPateYvwe6gtLBwjIb8pcY1gyh3uf7ALIfmx/eBgR683FCWq7oUXaOGLI+ScmtKip/RQOpMBkqYGLeDebdF1DIaw9pU+0YhVfw03BYj1x/pKlxwe7sY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785562975; c=relaxed/simple; bh=GALmEZvdh26PPGiAjWfxWB+e9ZYrjGLsH00RO4B1Xrw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=gl21O8FrjUjKu8YLkrRRcHUI55rPl8GTOejsagU8ZqEnDmNv7Vgbw9vaQUEGvL9fc3SaLRE+c3Tl2NYCAZwuIkcprsF9sS2k4gLGT0Bi649gT6Hbno2RqCHlVMBuKAPE3Ntc9YrJJoxldIQcCnF+Wo6NNjPOEbh5JOGMWAFOnyk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=P71mzTUM; arc=none smtp.client-ip=209.85.214.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="P71mzTUM" Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-2cf420670bbso1529515ad.1 for ; Fri, 31 Jul 2026 22:42:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785562972; x=1786167772; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=UYpVa28keFu2rtnNNRFvjEjsmc3FfTl8CCtVsMlnayI=; b=P71mzTUMNQzqQ9Bg8h+hYvh+09Ly5swIspPzZo8+X6afWF1D77F+B24/iM99V0UdF2 g28LKUK1ceaYghCdYNMH0nCaVFSB9O9f/16i7bhIrcypE3S2uiE4AvdCx7G9mAQ2aOhX 1oXufujMNviVN0GLSxsO1kiv/JDqxvuh+mQ2EVAIATJZvB5m72cw4PkyohX93fQvtdHF +SlbY/TeuT0JFe17UTlmrrvwQ++LjAyGARm37DXUvsPc/yPLttCLIpNrO5wg/pJLLqJ3 2WoPbN1TsDcKafjTVRDXAwU+0fPTSaPcGcX+YL1/V8+L1Ay5SQTcZsIAcMop4Sh8CUCv NtMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785562972; x=1786167772; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=UYpVa28keFu2rtnNNRFvjEjsmc3FfTl8CCtVsMlnayI=; b=a32z3u16YAbU1BEhs0PEsa6K6GgPiu47bQdA6DpFu8xArkEtlJCQHyk6SBCsG/dWZx x5DU7HJiF/OV2nLDQilo7Y6VnnlwRU1UlANLgWWzKkv8K6/oCpmu1HowZfGeECuLHoas tOcmcCxQUZgrTMWN/E8OP2i8DbzHGUD2GcgP7EuYLJ9GApC3zF0lzfJA+0A1p55bLH8E a43McMN8gNY2eI1Ilr3VRERieL29g6nGCoCFhgHQtNo/2kiSDehwlYi5PPegGsHn7FcN mXU0Wm6twm1moWqkV9bxoXM9mPzuq5WMlo2g4FnH0IVB9M6r0JfaREwAqvJwspx7Yj0w cm5Q== X-Gm-Message-State: AOJu0YxUU4fAD0DBjbWuG3oIbHNBjOYrC02FpT9UT6oionpuwcUQwtFg 0v3ujB0pfy3ntKkCfZ8BwO1FpNd2Xi+oSC/ryvWqNsgpesobvP1CVMVP X-Gm-Gg: AR+sD10zp7OwswaE8u1JKQJAoxoR2PHCvh0npvqojX4t0SOqHZ2a15urPCHYJBkKNTz b1jSvZvqeGaqobT04+Fm67rGm4aXK9dZWUM8egHCboOF3GnlZvlvChXgqO93QcdrsP+KjFbJrG4 vymtAGrAKm2TcSv2vSwNOLKR/T1YtKIhcJzLAm33pEFx5xRn2wG4rtSrk8Sfce3B13vkyzBbtg4 Q+uA/D+bltPJxVKk2HVwyjC30OjbCaMe+yi+wgQnM7/xjkzx48ptNNV+yZLi6uz2RAZrTNoBynl w8k2X0m3SsHs9OVsTEHv8TWyBGdG/Dg1kgRI9Mc6IN+Cs1zbz8esUc8z8n5Fs4qkjNjDW9u5UK9 L0T10zOLgDVZ18a61CrXcoh24zI6KNhGkvaA9CSroVpnzdWts0xAppj2oPsA2tlD/aGExFIbPOZ VJF0LEj3jJgVUWU5GhTjwOtQlr9IKnKsNYsVZKsRm1Vw67L44bnQLnWuHAGv20mX3FJVREFBqMC 7YS0MsSM9JrZF60/ITlRzS/pMx2wP5rdG9OWwbcvCKOlMbM0ITR2G4= X-Received: by 2002:a17:903:190:b0:2cf:7dfa:7f56 with SMTP id d9443c01a7336-2d052404e64mr34352655ad.2.1785562972005; Fri, 31 Jul 2026 22:42:52 -0700 (PDT) Received: from localhost.localdomain (45.78.65.84.16clouds.com. [45.78.65.84]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3153e18e70esm22692736eec.29.2026.07.31.22.42.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Jul 2026 22:42:51 -0700 (PDT) From: Chengfeng Ye To: Allison Henderson , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Santosh Shilimkar , Ka-Cheong Poon , Dan Carpenter Cc: netdev@vger.kernel.org, Kuniyuki Iwashima , linux-rdma@vger.kernel.org, rds-devel@oss.oracle.com, linux-kernel@vger.kernel.org, Chengfeng Ye Subject: [PATCH net-next v4] rds: synchronize info callbacks with module unload Date: Sat, 1 Aug 2026 13:42:34 +0800 Message-ID: <20260801054234.3535077-1-nicoyip.dev@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rds_info_getsockopt() reads a callback from rds_info_funcs and invokes it without protecting the callback's lifetime. Transport modules register functions stored in this array. For example, rds_tcp.ko registers rds_tcp_tc_info() for RDS_INFO_TCP_SOCKETS. This permits the following interleaving: CPU0 CPU1 rds_info_getsockopt() func = rds_tcp_tc_info rmmod rds_tcp rds_tcp_exit() rds_info_deregister_func() rds_info_funcs[offset] = NULL free rds_tcp module text func() The reader can therefore branch to an address in unloaded module text. Protect callback invocation with SRCU. Enter the SRCU read-side critical section before loading the callback and leave it only after the callback returns. Clear the callback with WRITE_ONCE() and call synchronize_srcu() before deregistration returns, preventing module unload from freeing its text while an old reader is still executing it. SRCU is required because callbacks such as RDS_INFO_COUNTERS can sleep. Keep the callback array unannotated and use READ_ONCE() and WRITE_ONCE() for concurrent slot access so sparse does not have to apply __rcu through the function-pointer typedef. Replace the two callback-slot BUG_ON() checks with WARN_ON_ONCE() and return without changing the slot on mismatch. Link: https://lore.kernel.org/netdev/20260720184955.3008978-1-nicoyip.dev@gmail.com/ Suggested-by: Allison Henderson Suggested-by: Kuniyuki Iwashima Reviewed-by: Allison Henderson Signed-off-by: Chengfeng Ye --- Changes in v4: - Use READ_ONCE() and WRITE_ONCE() because the callback pointer does not publish associated state requiring acquire/release ordering. - Keep the local variable declarations in reverse-Xmas-tree order. Link: https://lore.kernel.org/netdev/20260731160942.3245965-1-nicoyip.dev@gmail.com/ [v3] Changes in v3: - Use ordinary loads for callback-slot validation under rds_info_lock; retain acquire semantics only for the lockless reader. - Drop the Fixes tag because this patch targets net-next. - Add Allison Henderson's Reviewed-by tag. Link: https://lore.kernel.org/netdev/20260727174826.135662-1-nicoyip.dev@gmail.com/ [v2] Changes in v2: - Split the info callback/module-unload race from the independent inc->i_conn lifetime bug. - Keep the callback array unannotated and use smp_load_acquire() and smp_store_release() to resolve the sparse errors. - Replace the two touched callback-slot BUG_ON() checks with WARN_ON_ONCE() error paths. - Rewrite the commit message for the callback race and omit the unrelated inc->i_conn KASAN report. Link: https://lore.kernel.org/netdev/20260720184955.3008978-1-nicoyip.dev@gmail.com/ [v1] net/rds/info.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/net/rds/info.c b/net/rds/info.c index 21b32eb16559..31e7ad108459 100644 --- a/net/rds/info.c +++ b/net/rds/info.c @@ -32,6 +32,7 @@ */ #include #include +#include #include #include #include @@ -68,6 +69,7 @@ struct rds_info_iterator { unsigned long offset; }; +DEFINE_STATIC_SRCU(rds_info_srcu); static DEFINE_SPINLOCK(rds_info_lock); static rds_info_func rds_info_funcs[RDS_INFO_LAST - RDS_INFO_FIRST + 1]; @@ -78,8 +80,11 @@ void rds_info_register_func(int optname, rds_info_func func) BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); spin_lock(&rds_info_lock); - BUG_ON(rds_info_funcs[offset]); - rds_info_funcs[offset] = func; + if (WARN_ON_ONCE(rds_info_funcs[offset])) { + spin_unlock(&rds_info_lock); + return; + } + WRITE_ONCE(rds_info_funcs[offset], func); spin_unlock(&rds_info_lock); } EXPORT_SYMBOL_GPL(rds_info_register_func); @@ -91,9 +96,13 @@ void rds_info_deregister_func(int optname, rds_info_func func) BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); spin_lock(&rds_info_lock); - BUG_ON(rds_info_funcs[offset] != func); - rds_info_funcs[offset] = NULL; + if (WARN_ON_ONCE(rds_info_funcs[offset] != func)) { + spin_unlock(&rds_info_lock); + return; + } + WRITE_ONCE(rds_info_funcs[offset], NULL); spin_unlock(&rds_info_lock); + synchronize_srcu(&rds_info_srcu); } EXPORT_SYMBOL_GPL(rds_info_deregister_func); @@ -162,6 +171,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, sockopt_t *opt) + int srcu_idx; int npages = 0; int ret; int len; int total; len = opt->optlen; @@ -214,8 +224,10 @@ int rds_info_getsockopt(struct socket *sock, int optname, sockopt_t *opt) rdsdebug("len %d nr_pages %lu\n", len, nr_pages); call_func: - func = rds_info_funcs[optname - RDS_INFO_FIRST]; + srcu_idx = srcu_read_lock(&rds_info_srcu); + func = READ_ONCE(rds_info_funcs[optname - RDS_INFO_FIRST]); if (!func) { + srcu_read_unlock(&rds_info_srcu, srcu_idx); ret = -ENOPROTOOPT; goto out; } @@ -225,6 +237,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, sockopt_t *opt) iter.offset = offset0; func(sock, len, &iter, &lens); + srcu_read_unlock(&rds_info_srcu, srcu_idx); BUG_ON(lens.each == 0); total = lens.nr * lens.each; -- 2.43.0