From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 837742032D; Tue, 30 Sep 2025 15:27:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759246079; cv=none; b=f+W7052nIKVizDtsGG+8ggqrs+DPyEjmvWTElBIf1qU+BVFTHlJ2NTsh5N/9qghcJPNVgYE23cHHN1S7AIQAbPycpdr8+ErfKed/jhGRRuJKpqw0Uej3fchqCT8fD8FTyaqPEgcR9JcymOHXzcH662Pxs9gCLg3gpWbpKj8DkIo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759246079; c=relaxed/simple; bh=CFvWTAlaodFbE0o2Hq9TmUBVoeowRhnyKEmGwY8Vkq8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KI0mlRbaEJTmMuwVj+HRllGW9y9ZxADqYeNQmoq26g5uwRTdscis92HuujBFe/qBloMFazFf4q7gjk1SvUFimQRWD5nWr/3DZGyXoXHbUHXKJhn5kzNdtx9Uk+MCeLRMGYrviizTbrwcDS7h55USePlVN1s48c95xXXRsrrVAaI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RU8JNqTf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RU8JNqTf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B115EC4CEF0; Tue, 30 Sep 2025 15:27:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1759246079; bh=CFvWTAlaodFbE0o2Hq9TmUBVoeowRhnyKEmGwY8Vkq8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RU8JNqTfAeji2W+qcr+e6L0XhxV864NELBuZGZ5sKYN1i3GmPGY6pRosmvD4d6wRE z39OxEGw8cHJq6Jas5dMlh2ZJRjZYvbyI7PENrU+adEwYLiinJisGUEWPCe20H75Fl 9wS6qD9Z53UL1rkEMl/iasa4FHr49CmRLrH4meLc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mahanta Jambigi , Sidraya Jayagond , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 46/89] net/smc: fix warning in smc_rx_splice() when calling get_page() Date: Tue, 30 Sep 2025 16:48:00 +0200 Message-ID: <20250930143823.829462057@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250930143821.852512002@linuxfoundation.org> References: <20250930143821.852512002@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: Sidraya Jayagond [ Upstream commit a35c04de2565db191726b5741e6b66a35002c652 ] smc_lo_register_dmb() allocates DMB buffers with kzalloc(), which are later passed to get_page() in smc_rx_splice(). Since kmalloc memory is not page-backed, this triggers WARN_ON_ONCE() in get_page() and prevents holding a refcount on the buffer. This can lead to use-after-free if the memory is released before splice_to_pipe() completes. Use folio_alloc() instead, ensuring DMBs are page-backed and safe for get_page(). WARNING: CPU: 18 PID: 12152 at ./include/linux/mm.h:1330 smc_rx_splice+0xaf8/0xe20 [smc] CPU: 18 UID: 0 PID: 12152 Comm: smcapp Kdump: loaded Not tainted 6.17.0-rc3-11705-g9cf4672ecfee #10 NONE Hardware name: IBM 3931 A01 704 (z/VM 7.4.0) Krnl PSW : 0704e00180000000 000793161032696c (smc_rx_splice+0xafc/0xe20 [smc]) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Krnl GPRS: 0000000000000000 001cee80007d3001 00077400000000f8 0000000000000005 0000000000000001 001cee80007d3006 0007740000001000 001c000000000000 000000009b0c99e0 0000000000001000 001c0000000000f8 001c000000000000 000003ffcc6f7c88 0007740003e98000 0007931600000005 000792969b2ff7b8 Krnl Code: 0007931610326960: af000000 mc 0,0 0007931610326964: a7f4ff43 brc 15,00079316103267ea #0007931610326968: af000000 mc 0,0 >000793161032696c: a7f4ff3f brc 15,00079316103267ea 0007931610326970: e320f1000004 lg %r2,256(%r15) 0007931610326976: c0e53fd1b5f5 brasl %r14,000793168fd5d560 000793161032697c: a7f4fbb5 brc 15,00079316103260e6 0007931610326980: b904002b lgr %r2,%r11 Call Trace: smc_rx_splice+0xafc/0xe20 [smc] smc_rx_splice+0x756/0xe20 [smc]) smc_rx_recvmsg+0xa74/0xe00 [smc] smc_splice_read+0x1ce/0x3b0 [smc] sock_splice_read+0xa2/0xf0 do_splice_read+0x198/0x240 splice_file_to_pipe+0x7e/0x110 do_splice+0x59e/0xde0 __do_splice+0x11a/0x2d0 __s390x_sys_splice+0x140/0x1f0 __do_syscall+0x122/0x280 system_call+0x6e/0x90 Last Breaking-Event-Address: smc_rx_splice+0x960/0xe20 [smc] ---[ end trace 0000000000000000 ]--- Fixes: f7a22071dbf3 ("net/smc: implement DMB-related operations of loopback-ism") Reviewed-by: Mahanta Jambigi Signed-off-by: Sidraya Jayagond Link: https://patch.msgid.link/20250917184220.801066-1-sidraya@linux.ibm.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/smc/smc_loopback.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c index 3c5f64ca41153..85f0b7853b173 100644 --- a/net/smc/smc_loopback.c +++ b/net/smc/smc_loopback.c @@ -56,6 +56,7 @@ static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb, { struct smc_lo_dmb_node *dmb_node, *tmp_node; struct smc_lo_dev *ldev = smcd->priv; + struct folio *folio; int sba_idx, rc; /* check space for new dmb */ @@ -74,13 +75,16 @@ static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb, dmb_node->sba_idx = sba_idx; dmb_node->len = dmb->dmb_len; - dmb_node->cpu_addr = kzalloc(dmb_node->len, GFP_KERNEL | - __GFP_NOWARN | __GFP_NORETRY | - __GFP_NOMEMALLOC); - if (!dmb_node->cpu_addr) { + + /* not critical; fail under memory pressure and fallback to TCP */ + folio = folio_alloc(GFP_KERNEL | __GFP_NOWARN | __GFP_NOMEMALLOC | + __GFP_NORETRY | __GFP_ZERO, + get_order(dmb_node->len)); + if (!folio) { rc = -ENOMEM; goto err_node; } + dmb_node->cpu_addr = folio_address(folio); dmb_node->dma_addr = SMC_DMA_ADDR_INVALID; refcount_set(&dmb_node->refcnt, 1); @@ -122,7 +126,7 @@ static void __smc_lo_unregister_dmb(struct smc_lo_dev *ldev, write_unlock_bh(&ldev->dmb_ht_lock); clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask); - kvfree(dmb_node->cpu_addr); + folio_put(virt_to_folio(dmb_node->cpu_addr)); kfree(dmb_node); if (atomic_dec_and_test(&ldev->dmb_cnt)) -- 2.51.0