{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-72367", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-72367" ], "published": "2026-08-15T06:04:33Z", "summary": "iomap: guard io_size EOF trim against concurrent truncate underflow", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\niomap: guard io_size EOF trim against concurrent truncate underflow\n\niomap: fix zero padding data issue in concurrent append writes\nchanged ioend accounting so that io_size tracks only valid data\nwithin EOF. This trims io_size when a writeback range extends\npast end_pos:\n\n ioend->io_size += map_len;\n if (ioend->io_offset + ioend->io_size > end_pos)\n ioend->io_size = end_pos - ioend->io_offset;\n\nHowever, if end_pos ends up below ioend->io_offset, the subtraction\nbecomes negative and is stored in size_t io_size, causing an unsigned\nwrap to a huge value. This can happen when writeback continues past\nbyte-level EOF up to a block-aligned range, or when a concurrent\ntruncate shrinks the file after end_pos was sampled in\niomap_writeback_handle_eof().\n\nA wrapped io_size can mislead append detection and corrupt\ncompletion-time size handling, since filesystem end_io paths consume\nio_size for decisions such as on-disk EOF updates and unwritten/COW\ncompletion ranges.\n\nFix this by clamping io_size to zero when EOF has moved to or before\nthe ioend start offset. This preserves the original intent of trimming\nio_size to valid in-EOF data while avoiding the underflow.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.18.29-1+rpt1", "1:6.18.33-1+rpt1", "1:6.18.34-1+rpt1", "1:6.18.39-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.29+rpt-rpi-2712", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v6", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v7", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-2712", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v6", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v7", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-2712", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v6", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v7", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-2712", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v6", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v7", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt", "binary_version": "1:6.18.39-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.29-1+rpt1": { "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc", "upstream_version": "6.18.29", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" }, "1:6.18.33-1+rpt1": { "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412", "upstream_version": "6.18.33", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" }, "1:6.18.34-1+rpt1": { "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af", "upstream_version": "6.18.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" }, "1:6.18.39-1+rpt1": { "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff", "upstream_version": "6.18.39", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.40" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-72367" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/1f38f65bf965fce9aa159d45c5347538f56c5973" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/7f7780abb4c0fdc9a2603aea8e985ff14ee900e0" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/55ec50d046c03b3724741957f7b007856e36dbe7" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-17T05:50:24Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 8.8, "cvss_v3_severity": "High", "scenario": "AV:N - On XFS/GFS2/NTFS backends exposed via nfsd or ksmbd, a remote client can trigger iomap buffered writeback by issuing concurrent WRITE and truncate/SETATTR operations over the network without local shell access.\nAC:L - The attacker controls both sides of the race by concurrently writing dirty pages and truncating the same file (local threads or parallel NFS/SMB requests); no uncontrollable memory layout or rare kernel configuration is required.\nPR:L - Exploitation requires write and truncate permission on the target file (authenticated NFS/SMB client or local unprivileged user with file write access); this is not a pre-authentication network code path.\nUI:N - No victim interaction is needed beyond the attacker's own write and truncate I/O; writeback is driven automatically by the VFS/page-cache path once pages are dirtied.\nS:U - Impact is confined to kernel/filesystem integrity within the same security authority (metadata corruption, incorrect extent completion, possible local privilege escalation), not a VM escape or cross-authority boundary.\nC:H - A wrapped io_size propagates into XFS completion paths (COW convert/end, unwritten conversion, append detection), potentially remapping or exposing unintended on-disk extents and data beyond the legitimate EOF-trimmed range.\nI:H - Huge bogus io_size drives xfs_reflink_convert_cow, xfs_reflink_end_cow, xfs_iomap_write_unwritten, and xfs_setfilesize with corrupted ranges, enabling incorrect on-disk metadata updates and file content modification.\nA:H - Corrupted ioend accounting can trigger pathological XFS extent walks, ASSERT failures, filesystem shutdown, or hung writeback during I/O completion, causing kernel oops or sustained denial of service." } } }