From nobody Sun Feb 8 18:31:42 2026 Received: from ewsoutbound.kpnmail.nl (ewsoutbound.kpnmail.nl [195.121.94.167]) (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 8228436999F for ; Tue, 28 Oct 2025 23:24:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.121.94.167 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761693881; cv=none; b=jsVzZ3+g5L/b6lnpioqBkS6uZ5o1WfP50VkWOZQ05bBUnXDfEe5h8TMIBh9cLNBvwkM4xumvfNlRcHBOQrnVb/jXje6MTUUjBQMVEeC6BI031V3amXuInJHXad4b66DG6SBtzVO19xumQIUCYcRnONcNc64RMqDBwMiLOIiTf9A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761693881; c=relaxed/simple; bh=439yTsJFgai9ffO9s16hEvRBsetv/V8ej97KerPugMA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=UI/WTTtQSd2kL/zwoPA5XwAX9Rj2pl+jTIfwVGQd5f3RDc9uaGzmR8r9/4SqJTpavvUy0NHSypiR/lmqBa4xuopCfCtFj2u4DU4j8/SqHb/e5NKhDSGWQouHm0iFmibtDIQ6mdqEpdUvAOq4XMH3iAYsMelp+2ox5Uaw/UtJ5pA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xs4all.nl; spf=pass smtp.mailfrom=xs4all.nl; dkim=pass (2048-bit key) header.d=xs4all.nl header.i=@xs4all.nl header.b=R14oSUjh; arc=none smtp.client-ip=195.121.94.167 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xs4all.nl Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xs4all.nl Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=xs4all.nl header.i=@xs4all.nl header.b="R14oSUjh" X-KPN-MessageId: 653a8817-b455-11f0-a27d-005056abbe64 Received: from smtp.kpnmail.nl (unknown [10.31.155.40]) by ewsoutbound.so.kpn.org (Halon) with ESMTPS id 653a8817-b455-11f0-a27d-005056abbe64; Wed, 29 Oct 2025 00:25:31 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xs4all.nl; s=xs4all01; h=mime-version:message-id:date:subject:to:from; bh=CwganTJx+9Lw3WMSh7k5X4jbPqLypnHQOM2bPJvw16Q=; b=R14oSUjhmj2pquwuRCcE8NiEP8x8ux60XVc+D6ACcpVcOffL06DqgXioV5ukDUBDD5I99jIDX3qmj a5ahmErglsZG2hwdWOOBMZ/lHAN+BfB6IkbcJmCOpchiX+QIoRtvZAcdD2Ax6xlvWM6GBFi7Fxrr2W oaGqr2I0XLSbTzQ5xeQHiekciMJ1lXtLC2qWqFKvytepAWQL2BOD7VrX4GSGM+BFBvssC7v289y8Wh pEXnnRkSUHUewp2x+kSy8xPU1JtdV/CXCcfYbG5JCdn/rBHCTOG8cR3tE3Fkfw3UaAi/EG/9fLZeW9 KUJ6fGpPGXROAUgV35GN7BGer1Uh3bg== X-KPN-MID: 33|tzsCuW5x5QBoQxv6qLKTGow+iGUfXhzRjhiA/IpHMov+l+P/osS1hjmYvK8DuM6 qeQra2J/YrM0pPdh4lWEJYuMx04EuMGg6QXV0aP2ppkk= X-KPN-VerifiedSender: Yes X-CMASSUN: 33|fMvmz9POJ2hi8AxioCD6qmoiI1Oyk2u6fX/3p9Nolvil3pAoWorKv8vPcatxfVT UEdrhNBTfuylyjoVoH1khfw== Received: from daedalus.home (unknown [178.231.9.54]) by smtp.xs4all.nl (Halon) with ESMTPSA id 1c1539a7-b455-11f0-b8c6-005056ab7584; Wed, 29 Oct 2025 00:23:29 +0100 (CET) From: Jori Koolstra To: Dave Kleikamp , Jeff Layton , Christian Brauner , Gabriel Krisman Bertazi , NeilBrown , Al Viro Cc: jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org, jkoolstra@xs4all.nl, syzbot+cd7590567cc388f064f3@syzkaller.appspotmail.com Subject: [PATCH] dtInsertEntry can result in buffer overflow on corrupted jfs filesystems Date: Wed, 29 Oct 2025 00:23:29 +0100 Message-ID: <20251028232329.430752-1-jkoolstra@xs4all.nl> X-Mailer: git-send-email 2.51.1.dirty Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Syzbot reported a general protection fault in inode_set_ctime_current. This resulted from the following circumstances: when creating a new file via dtInsert, BT_GETSEARCH may yield a pointer to a dtroot which is embedded directly in the jfs_inode_info. When finally dtInsertEntry is called, if the freelist field or any next field of a slot of the dtpage is corrupted, this may result in memory corruption of the parent directory inode. In this case the i_sb field was corrupted, which raised the gpf when in inode_set_ctime_current i_sb was dereferenced to access s_time_gran. I tested the patch using the syzbot reproducer and doing some basic filesystem operations on a fresh jfs fs, such as "cp -r /usr/include/ /mnt/jfs/" and "rm -r /mnt/jfs/include/n*" Signed-off-by: Jori Koolstra Reported-by: syzbot+cd7590567cc388f064f3@syzkaller.appspotmail.com Closes: https://syzbot.org/bug?extid=3Dcd7590567cc388f064f3 --- fs/jfs/jfs_dtree.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c index 0ab83bb7bbdf..e37278596afe 100644 --- a/fs/jfs/jfs_dtree.c +++ b/fs/jfs/jfs_dtree.c @@ -170,8 +170,8 @@ static void dtGetKey(dtpage_t * p, int i, struct compon= ent_name * key, static int ciGetLeafPrefixKey(dtpage_t * lp, int li, dtpage_t * rp, int ri, struct component_name * key, int flag); =20 -static void dtInsertEntry(dtpage_t * p, int index, struct component_name *= key, - ddata_t * data, struct dt_lock **); +static int dtInsertEntry(dtpage_t * p, int index, struct component_name * = key, + ddata_t * data, struct dt_lock **); =20 static void dtMoveEntry(dtpage_t * sp, int si, dtpage_t * dp, struct dt_lock ** sdtlock, struct dt_lock ** ddtlock, @@ -891,7 +891,8 @@ int dtInsert(tid_t tid, struct inode *ip, lv->length =3D 1; dtlck->index++; =20 - dtInsertEntry(p, index, name, &data, &dtlck); + if ((rc =3D dtInsertEntry(p, index, name, &data, &dtlck))) + return rc; =20 /* linelock stbl of non-root leaf page */ if (!(p->header.flag & BT_ROOT)) { @@ -3625,9 +3626,10 @@ static void dtGetKey(dtpage_t * p, int i, /* entry i= ndex */ * function: allocate free slot(s) and * write a leaf/internal entry * - * return: entry slot index + * * return: 0 - success; + * errno - failure; */ -static void dtInsertEntry(dtpage_t * p, int index, struct component_name *= key, +static int dtInsertEntry(dtpage_t * p, int index, struct component_name * = key, ddata_t * data, struct dt_lock ** dtlock) { struct dtslot *h, *t; @@ -3649,6 +3651,10 @@ static void dtInsertEntry(dtpage_t * p, int index, s= truct component_name * key, =20 /* allocate a free slot */ hsi =3D fsi =3D p->header.freelist; + if (fsi >=3D ((p->header.flag & BT_ROOT) ? DTROOTMAXSLOT : p->header.maxs= lot)) { + jfs_err("Encountered corrupted dtpage before insert"); + return -EIO; + } h =3D &p->slot[fsi]; p->header.freelist =3D h->next; --p->header.freecnt; @@ -3697,6 +3703,10 @@ static void dtInsertEntry(dtpage_t * p, int index, s= truct component_name * key, while (klen) { /* get free slot */ fsi =3D p->header.freelist; + if (fsi >=3D ((p->header.flag & BT_ROOT) ? DTROOTMAXSLOT : p->header.max= slot)) { + jfs_err("Encountered corrupted dtpage before insert"); + return -EIO; + } t =3D &p->slot[fsi]; p->header.freelist =3D t->next; --p->header.freecnt; @@ -3774,6 +3784,8 @@ static void dtInsertEntry(dtpage_t * p, int index, st= ruct component_name * key, =20 /* advance next available entry index of stbl */ ++p->header.nextindex; + + return 0; } =20 =20 --=20 2.51.1.dirty