CVE-2023-53485 (GCVE-0-2023-53485)
Vulnerability from cvelistv5
Published
2025-10-01 11:42
Modified
2026-08-05 09:14
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: fs: jfs: Fix UBSAN: array-index-out-of-bounds in dbAllocDmapLev Syzkaller reported the following issue: UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:1965:6 index -84 is out of range for type 's8[341]' (aka 'signed char[341]') CPU: 1 PID: 4995 Comm: syz-executor146 Not tainted 6.4.0-rc6-syzkaller-00037-gb6dad5178cea #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348 dbAllocDmapLev+0x3e5/0x430 fs/jfs/jfs_dmap.c:1965 dbAllocCtl+0x113/0x920 fs/jfs/jfs_dmap.c:1809 dbAllocAG+0x28f/0x10b0 fs/jfs/jfs_dmap.c:1350 dbAlloc+0x658/0xca0 fs/jfs/jfs_dmap.c:874 dtSplitUp fs/jfs/jfs_dtree.c:974 [inline] dtInsert+0xda7/0x6b00 fs/jfs/jfs_dtree.c:863 jfs_create+0x7b6/0xbb0 fs/jfs/namei.c:137 lookup_open fs/namei.c:3492 [inline] open_last_lookups fs/namei.c:3560 [inline] path_openat+0x13df/0x3170 fs/namei.c:3788 do_filp_open+0x234/0x490 fs/namei.c:3818 do_sys_openat2+0x13f/0x500 fs/open.c:1356 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1383 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f1f4e33f7e9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc21129578 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1f4e33f7e9 RDX: 000000000000275a RSI: 0000000020000040 RDI: 00000000ffffff9c RBP: 00007f1f4e2ff080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1f4e2ff110 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> The bug occurs when the dbAllocDmapLev()function attempts to access dp->tree.stree[leafidx + LEAFIND] while the leafidx value is negative. To rectify this, the patch introduces a safeguard within the dbAllocDmapLev() function. A check has been added to verify if leafidx is negative. If it is, the function immediately returns an I/O error, preventing any further execution that could potentially cause harm. Tested via syzbot.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
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          "programFiles": [
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs: jfs: Fix UBSAN: array-index-out-of-bounds in dbAllocDmapLev\n\nSyzkaller reported the following issue:\n\nUBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:1965:6\nindex -84 is out of range for type \u0027s8[341]\u0027 (aka \u0027signed char[341]\u0027)\nCPU: 1 PID: 4995 Comm: syz-executor146 Not tainted 6.4.0-rc6-syzkaller-00037-gb6dad5178cea #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023\nCall Trace:\n \u003cTASK\u003e\n __dump_stack lib/dump_stack.c:88 [inline]\n dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106\n ubsan_epilogue lib/ubsan.c:217 [inline]\n __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348\n dbAllocDmapLev+0x3e5/0x430 fs/jfs/jfs_dmap.c:1965\n dbAllocCtl+0x113/0x920 fs/jfs/jfs_dmap.c:1809\n dbAllocAG+0x28f/0x10b0 fs/jfs/jfs_dmap.c:1350\n dbAlloc+0x658/0xca0 fs/jfs/jfs_dmap.c:874\n dtSplitUp fs/jfs/jfs_dtree.c:974 [inline]\n dtInsert+0xda7/0x6b00 fs/jfs/jfs_dtree.c:863\n jfs_create+0x7b6/0xbb0 fs/jfs/namei.c:137\n lookup_open fs/namei.c:3492 [inline]\n open_last_lookups fs/namei.c:3560 [inline]\n path_openat+0x13df/0x3170 fs/namei.c:3788\n do_filp_open+0x234/0x490 fs/namei.c:3818\n do_sys_openat2+0x13f/0x500 fs/open.c:1356\n do_sys_open fs/open.c:1372 [inline]\n __do_sys_openat fs/open.c:1388 [inline]\n __se_sys_openat fs/open.c:1383 [inline]\n __x64_sys_openat+0x247/0x290 fs/open.c:1383\n do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\nRIP: 0033:0x7f1f4e33f7e9\nCode: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 \u003c48\u003e 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007ffc21129578 EFLAGS: 00000246 ORIG_RAX: 0000000000000101\nRAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1f4e33f7e9\nRDX: 000000000000275a RSI: 0000000020000040 RDI: 00000000ffffff9c\nRBP: 00007f1f4e2ff080 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 00007f1f4e2ff110\nR13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000\n \u003c/TASK\u003e\n\nThe bug occurs when the dbAllocDmapLev()function attempts to access\ndp-\u003etree.stree[leafidx + LEAFIND] while the leafidx value is negative.\n\nTo rectify this, the patch introduces a safeguard within the\ndbAllocDmapLev() function. A check has been added to verify if leafidx is\nnegative. If it is, the function immediately returns an I/O error, preventing\nany further execution that could potentially cause harm.\n\nTested via syzbot."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is reached through local syscalls (`openat(O_CREAT)` on a mounted JFS volume) after a crafted JFS image is attached; there is no network-facing consumer of this code.\nAC:L - The attacker fully controls the on-disk `dmt_leafidx`/`start` fields of the dmap page, so the negative index and the resulting bogus block number are produced deterministically on the first file creation \u2014 no race or unpredictable state is involved.\nPR:L - An unprivileged local user suffices in realistic deployments \u2014 udisks2/autofs on desktops, kiosks and shared workstations loop-mount or auto-mount user-supplied JFS media without root, after which any write to the mounted directory reaches `dbAlloc()`.\nUI:N - The attacker performs every step themselves (supply the image, have it auto/loop-mounted, create a file); no action by a separate victim user is required.\nS:U - The corruption stays within the kernel\u0027s own security authority \u2014 standard in-kernel memory and filesystem-metadata corruption with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - `stree[leafidx + LEAFIND]` and `dp-\u003ewmap[leafidx]` are read at an unvalidated, attacker-chosen negative offset (`dmt_leafidx` is a full `__le32`), giving an unbounded out-of-bounds read of kernel memory whose contents steer the subsequent block-allocation result and are thus observable.\nI:H - The bogus `blkno` propagates into `dbAllocBits()`, where `bmp-\u003edb_agfree[agno] -= nblocks` writes at an attacker-influenced out-of-range index of the kmalloc\u0027d `struct bmap`, and into `dbSplit()`/`dbAdjTree()`, which write past the metapage using the same unvalidated `dmt_leafidx` \u2014 heap out-of-bounds writes usable for control-flow corruption.\nA:H - A far-negative index dereferences unmapped memory and the corrupted allocation state feeds `jfs_error()`/inconsistent block accounting, producing a kernel oops or panic that the attacker can trigger at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:14:20.042Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0d9e678a82915633b99603f744e7735d1a673d72"
        },
        {
          "url": "https://git.kernel.org/stable/c/53b0a362aca2583729e8ca2936ca657ff3247d88"
        },
        {
          "url": "https://git.kernel.org/stable/c/6e7d9d76e5654bcdd3cdb7c9441a8113428ecebb"
        },
        {
          "url": "https://git.kernel.org/stable/c/911b48eec45152822bccf45cd3563b48256b1520"
        },
        {
          "url": "https://git.kernel.org/stable/c/39f6292d75959e8accac0b3e24090094ba0824e9"
        },
        {
          "url": "https://git.kernel.org/stable/c/bdf07ab1595b613b03f32dbb5cb379edfa1a7334"
        },
        {
          "url": "https://git.kernel.org/stable/c/f2af019091f904ca08b3572ab0111238ad6d17b3"
        },
        {
          "url": "https://git.kernel.org/stable/c/4e302336d5ca1767a06beee7596a72d3bdc8d983"
        }
      ],
      "title": "fs: jfs: Fix UBSAN: array-index-out-of-bounds in dbAllocDmapLev",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2023-53485",
    "datePublished": "2025-10-01T11:42:53.337Z",
    "dateReserved": "2025-10-01T11:39:39.402Z",
    "dateUpdated": "2026-08-05T09:14:20.042Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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