{ "cveId": "CVE-2023-53143", "url": "https://patchblox.com/security/cve/CVE-2023-53143", "summary": "CVE-2023-53143 is fixed in 20 products on 1 platform, first by ALAS2023-2023-148, released March 30, 2023. It is not reported as exploited. Patch Radar priority: Routine.", "title": "linux: In the Linux kernel, the following vulnerability has been resolved: ext4: fix another off-by-one fsmap error on 1k b...", "description": "In the Linux kernel, the following vulnerability has been resolved: ext4: fix another off-by-one fsmap error on 1k block filesystems Apparently syzbot figured out that issuing this FSMAP call: struct fsmap_head cmd = { \t.fmh_count\t= ...; \t.fmh_keys\t= { \t\t{ .fmr_device = /* ext4 dev */, .fmr_physical = 0, }, \t\t{ .fmr_device = /* ext4 dev */, .fmr_physical = 0, }, \t}, ... }; ret = ioctl(fd, FS_IOC_GETFSMAP, \u0026cmd); Produces this crash if the underlying filesystem is a 1k-block ext4 filesystem: kernel BUG at fs/ext4/ext4.h:3331! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 3 PID: 3227965 Comm: xfs_io Tainted: G W O 6.2.0-rc8-achx Hardware name: QEMU Standard PC (Q35 \u002B ICH9, 2009), BIOS 1.15.0-1 04/01/2014 RIP: 0010:ext4_mb_load_buddy_gfp\u002B0x47c/0x570 [ext4] RSP: 0018:ffffc90007c03998 EFLAGS: 00010246 RAX: ffff888004978000 RBX: ffffc90007c03a20 RCX: ffff888041618000 RDX: 0000000000000000 RSI: 00000000000005a4 RDI: ffffffffa0c99b11 RBP: ffff888012330000 R08: ffffffffa0c2b7d0 R09: 0000000000000400 R10: ffffc90007c03950 R11: 0000000000000000 R12: 0000000000000001 R13: 00000000ffffffff R14: 0000000000000c40 R15: ffff88802678c398 FS: 00007fdf2020c880(0000) GS:ffff88807e100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffd318a5fe8 CR3: 000000007f80f001 CR4: 00000000001706e0 Call Trace: \u003CTASK\u003E ext4_mballoc_query_range\u002B0x4b/0x210 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80] ext4_getfsmap_datadev\u002B0x713/0x890 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80] ext4_getfsmap\u002B0x2b7/0x330 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80] ext4_ioc_getfsmap\u002B0x153/0x2b0 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80] __ext4_ioctl\u002B0x2a7/0x17e0 [ext4 dfa189daddffe8fecd3cdfd00564e0f265a8ab80] __x64_sys_ioctl\u002B0x82/0xa0 do_syscall_64\u002B0x2b/0x80 entry_SYSCALL_64_after_hwframe\u002B0x46/0xb0 RIP: 0033:0x7fdf20558aff RSP: 002b:00007ffd318a9e30 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000000200c0 RCX: 00007fdf20558aff RDX: 00007fdf1feb2010 RSI: 00000000c0c0583b RDI: 0000000000000003 RBP: 00005625c0634be0 R08: 00005625c0634c40 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdf1feb2010 R13: 00005625be70d994 R14: 0000000000000800 R15: 0000000000000000 For GETFSMAP calls, the caller selects a physical block device by writing its block number into fsmap_head.fmh_keys[01].fmr_device. To query mappings for a subrange of the device, the starting byte of the range is written to fsmap_head.fmh_keys[0].fmr_physical and the last byte of the range goes in fsmap_head.fmh_keys[1].fmr_physical. IOWs, to query what mappings overlap with bytes 3-14 of /dev/sda, you\u0027d set the inputs as follows: \tfmh_keys[0] = { .fmr_device = major(8, 0), .fmr_physical = 3}, \tfmh_keys[1] = { .fmr_device = major(8, 0), .fmr_physical = 14}, Which would return you whatever is mapped in the 12 bytes starting at physical offset 3. The crash is due to insufficient range validation of keys[1] in ext4_getfsmap_datadev. On 1k-block filesystems, block 0 is not part of the filesystem, which means that s_first_data_block is nonzero. ext4_get_group_no_and_offset subtracts this quantity from the blocknr argument before cracking it into a group number and a block number within a group. IOWs, block group 0 spans blocks 1-8192 (1-based) instead of 0-8191 (0-based) like what happens with larger blocksizes. The net result of this encoding is that blocknr \u003C s_first_data_block is not a valid input to this function. The end_fsb variable is set from the keys that are copied from userspace, which means that in the above example, its value is zero. That leads to an underflow here: \tblocknr = blocknr - le32_to_cpu(es-\u003Es_first_data_block); The division then operates on -1: \toffset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) \u003E\u003E \t\tEXT4_SB(sb)-\u003Es_cluster_bits; Leaving an impossibly large group number (2^32-1) in blocknr. ext4_getfsmap_check_keys checked that keys[0 ---truncated---", "published": "2023-03-30T21:11:00Z", "severity": "medium", "cvss": 5.5, "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "epss": 0.00194, "epssPercentile": 0.09128, "priority": "Routine", "priorityTier": 4, "exploited": false, "vendorExploited": false, "disclosed": false, "fixes": [ { "platform": "linux", "product": "bpftool", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "bpftool-debuginfo", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-debuginfo", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-debuginfo-common-aarch64", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-debuginfo-common-x86_64", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-devel", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-headers", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-libbpf", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-libbpf-devel", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-libbpf-static", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-livepatch-6.1.21-1.45", "release": "amzn 2023", "fixedVersion": "1.0-0.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-tools", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-tools-debuginfo", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "kernel-tools-devel", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "linux", "release": "Debian 12.15 (bookworm)", "fixedVersion": "6.1.20-1", "fix": "DEBIAN-CVE-2023-53143", "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-53143", "released": "2025-05-02T16:15:33Z" }, { "platform": "linux", "product": "linux", "release": "Debian 13.5 (trixie)", "fixedVersion": "6.1.20-1", "fix": "DEBIAN-CVE-2023-53143", "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-53143", "released": "2025-05-02T16:15:33Z" }, { "platform": "linux", "product": "linux", "release": "Debian 14", "fixedVersion": "6.1.20-1", "fix": "DEBIAN-CVE-2023-53143", "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-53143", "released": "2025-05-02T16:15:33Z" }, { "platform": "linux", "product": "perf", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "perf-debuginfo", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "python3-perf", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" }, { "platform": "linux", "product": "python3-perf-debuginfo", "release": "amzn 2023", "fixedVersion": "6.1.21-1.45.amzn2023", "fix": "ALAS2023-2023-148", "url": "https://patchblox.com/security/fix/linux/alas2023-2023-148", "released": "2023-03-30T21:11:00Z" } ], "noFixYet": [], "dataAsOf": "2026-11-09T01:18:40Z", "attribution": { "text": "Data: Patchblox Patch Radar", "url": "https://patchblox.com/security/patch-radar", "terms": "https://patchblox.com/security/patch-radar/use-the-data" } }