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GET /api/patches/2216343/?format=api
{ "id": 2216343, "url": "http://patchwork.ozlabs.org/api/patches/2216343/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260326104544.509518-3-dhowells@redhat.com/", "project": { "id": 12, "url": "http://patchwork.ozlabs.org/api/projects/12/?format=api", "name": "Linux CIFS Client", "link_name": "linux-cifs-client", "list_id": "linux-cifs.vger.kernel.org", "list_email": "linux-cifs@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260326104544.509518-3-dhowells@redhat.com>", "list_archive_url": null, "date": "2026-03-26T10:45:17", "name": "[02/26] netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "e44fce97ddf35daca71230d9f97cd23b764d450d", "submitter": { "id": 59, "url": "http://patchwork.ozlabs.org/api/people/59/?format=api", "name": "David Howells", "email": "dhowells@redhat.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260326104544.509518-3-dhowells@redhat.com/mbox/", "series": [ { "id": 497565, "url": "http://patchwork.ozlabs.org/api/series/497565/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=497565", "date": "2026-03-26T10:45:15", "name": "netfs: Keep track of folios in a segmented bio_vec[] chain", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/497565/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2216343/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2216343/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linux-cifs+bounces-10525-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-cifs@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=KMpRow1I;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=104.64.211.4; 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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n\ts=mimecast20190719; t=1774521993;\n\th=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n\t to:to:cc:cc:mime-version:mime-version:\n\t content-transfer-encoding:content-transfer-encoding:\n\t in-reply-to:in-reply-to:references:references;\n\tbh=MVVzRK3Tmywza1SU8JPOcR6dARnvIl+M3c8pioBtMpU=;\n\tb=KMpRow1I0ytgwqfiM15ZP1oRhxIY/hf2Xmfy2/Fw5qdNQiUuKHip8WtNWpjNwKVdIf1L2l\n\t28A9BU/rOvUDbOQliVtTs9kQMQI3lLqKypm5lzj4PC6TLPjRwTeue753YIEovZP4N49apQ\n\tPaYtJvkuUIfEfGwM25juOsMXxAWWNe0=", "X-MC-Unique": "bkvv3eYQNDWdQ1hrbBSehg-1", "X-Mimecast-MFC-AGG-ID": "bkvv3eYQNDWdQ1hrbBSehg_1774521985", "From": "David Howells <dhowells@redhat.com>", "To": "Christian Brauner <christian@brauner.io>,\n\tMatthew Wilcox <willy@infradead.org>,\n\tChristoph Hellwig <hch@infradead.org>", "Cc": "David Howells <dhowells@redhat.com>,\n\tPaulo Alcantara <pc@manguebit.com>,\n\tJens Axboe <axboe@kernel.dk>,\n\tLeon Romanovsky <leon@kernel.org>,\n\tSteve French <sfrench@samba.org>,\n\tChenXiaoSong <chenxiaosong@chenxiaosong.com>,\n\tMarc Dionne <marc.dionne@auristor.com>,\n\tEric Van Hensbergen <ericvh@kernel.org>,\n\tDominique Martinet <asmadeus@codewreck.org>,\n\tIlya Dryomov <idryomov@gmail.com>,\n\tTrond Myklebust <trondmy@kernel.org>,\n\tnetfs@lists.linux.dev,\n\tlinux-afs@lists.infradead.org,\n\tlinux-cifs@vger.kernel.org,\n\tlinux-nfs@vger.kernel.org,\n\tceph-devel@vger.kernel.org,\n\tv9fs@lists.linux.dev,\n\tlinux-erofs@lists.ozlabs.org,\n\tlinux-fsdevel@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org,\n\tDeepanshu Kartikey <kartikey406@gmail.com>,\n\tsyzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com,\n\tDeepanshu Kartikey <Kartikey406@gmail.com>", "Subject": "[PATCH 02/26] netfs: Fix kernel BUG in netfs_limit_iter() for\n ITER_KVEC iterators", "Date": "Thu, 26 Mar 2026 10:45:17 +0000", "Message-ID": "<20260326104544.509518-3-dhowells@redhat.com>", "In-Reply-To": "<20260326104544.509518-1-dhowells@redhat.com>", "References": "<20260326104544.509518-1-dhowells@redhat.com>", "Precedence": "bulk", "X-Mailing-List": "linux-cifs@vger.kernel.org", "List-Id": "<linux-cifs.vger.kernel.org>", "List-Subscribe": "<mailto:linux-cifs+subscribe@vger.kernel.org>", "List-Unsubscribe": "<mailto:linux-cifs+unsubscribe@vger.kernel.org>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-Scanned-By": "MIMEDefang 3.4.1 on 10.30.177.93" }, "content": "From: Deepanshu Kartikey <kartikey406@gmail.com>\n\nWhen a process crashes and the kernel writes a core dump to a 9P\nfilesystem, __kernel_write() creates an ITER_KVEC iterator. This\niterator reaches netfs_limit_iter() via netfs_unbuffered_write(), which\nonly handles ITER_FOLIOQ, ITER_BVEC and ITER_XARRAY iterator types,\nhitting the BUG() for any other type.\n\nFix this by adding netfs_limit_kvec() following the same pattern as\nnetfs_limit_bvec(), since both kvec and bvec are simple segment arrays\nwith pointer and length fields. Dispatch it from netfs_limit_iter() when\nthe iterator type is ITER_KVEC.\n\nFixes: cae932d3aee5 (\"netfs: Add func to calculate pagecount/size-limited span of an iterator\")\nReported-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com\nCloses: https://syzkaller.appspot.com/bug?extid=9c058f0d63475adc97fd\nTested-by: syzbot+9c058f0d63475adc97fd@syzkaller.appspotmail.com\nSigned-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>\nSigned-off-by: David Howells <dhowells@redhat.com>\n---\n fs/netfs/iterator.c | 43 +++++++++++++++++++++++++++++++++++++++++++\n 1 file changed, 43 insertions(+)", "diff": "diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c\nindex 72a435e5fc6d..154a14bb2d7f 100644\n--- a/fs/netfs/iterator.c\n+++ b/fs/netfs/iterator.c\n@@ -142,6 +142,47 @@ static size_t netfs_limit_bvec(const struct iov_iter *iter, size_t start_offset,\n \treturn min(span, max_size);\n }\n \n+/*\n+ * Select the span of a kvec iterator we're going to use. Limit it by both\n+ * maximum size and maximum number of segments. Returns the size of the span\n+ * in bytes.\n+ */\n+static size_t netfs_limit_kvec(const struct iov_iter *iter, size_t start_offset,\n+\t\t\t size_t max_size, size_t max_segs)\n+{\n+\tconst struct kvec *kvecs = iter->kvec;\n+\tunsigned int nkv = iter->nr_segs, ix = 0, nsegs = 0;\n+\tsize_t len, span = 0, n = iter->count;\n+\tsize_t skip = iter->iov_offset + start_offset;\n+\n+\tif (WARN_ON(!iov_iter_is_kvec(iter)) ||\n+\t WARN_ON(start_offset > n) ||\n+\t n == 0)\n+\t\treturn 0;\n+\n+\twhile (n && ix < nkv && skip) {\n+\t\tlen = kvecs[ix].iov_len;\n+\t\tif (skip < len)\n+\t\t\tbreak;\n+\t\tskip -= len;\n+\t\tn -= len;\n+\t\tix++;\n+\t}\n+\n+\twhile (n && ix < nkv) {\n+\t\tlen = min3(n, kvecs[ix].iov_len - skip, max_size);\n+\t\tspan += len;\n+\t\tnsegs++;\n+\t\tix++;\n+\t\tif (span >= max_size || nsegs >= max_segs)\n+\t\t\tbreak;\n+\t\tskip = 0;\n+\t\tn -= len;\n+\t}\n+\n+\treturn min(span, max_size);\n+}\n+\n /*\n * Select the span of an xarray iterator we're going to use. Limit it by both\n * maximum size and maximum number of segments. It is assumed that segments\n@@ -245,6 +286,8 @@ size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,\n \t\treturn netfs_limit_bvec(iter, start_offset, max_size, max_segs);\n \tif (iov_iter_is_xarray(iter))\n \t\treturn netfs_limit_xarray(iter, start_offset, max_size, max_segs);\n+\tif (iov_iter_is_kvec(iter))\n+\t\treturn netfs_limit_kvec(iter, start_offset, max_size, max_segs);\n \tBUG();\n }\n EXPORT_SYMBOL(netfs_limit_iter);\n", "prefixes": [ "02/26" ] }