CyberSecBulletin
CVE-2023-53485NVD status: Modified

Linux: Improper Validation of Array Index

Published Updated By the CyberSecBulletin desk

CVE-2023-53485 is a high-severity improper validation of array index vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 0d9e678a82915633b99603f744e7735d1a673d72, 53b0a362aca2583729e8ca2936ca657ff3247d88, 6e7d9d76e5654bcdd3cdb7c9441a8113428ecebb as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 0d9e678a82915633b99603f744e7735d1a673d72 or 53b0a362aca2583729e8ca2936ca657ff3247d88 or 6e7d9d76e5654bcdd3cdb7c9441a8113428ecebb or 911b48eec45152822bccf45cd3563b48256b1520, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.14.324 or 4.19.293 or 5.4.255 or 5.10.192, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 0d9e678a82915633b99603f744e7735d1a673d72; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 53b0a362aca2583729e8ca2936ca657ff3247d88; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6e7d9d76e5654bcdd3cdb7c9441a8113428ecebb; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 911b48eec45152822bccf45cd3563b48256b1520; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 39f6292d75959e8accac0b3e24090094ba0824e9; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, bdf07ab1595b613b03f32dbb5cb379edfa1a7334; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, f2af019091f904ca08b3572ab0111238ad6d17b3; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 4e302336d5ca1767a06beee7596a72d3bdc8d983; and 1 more ranges0d9e678a82915633b99603f744e7735d1a673d72, 53b0a362aca2583729e8ca2936ca657ff3247d88, 6e7d9d76e5654bcdd3cdb7c9441a8113428ecebb, 911b48eec45152822bccf45cd3563b48256b1520, 39f6292d75959e8accac0b3e24090094ba0824e9, bdf07ab1595b613b03f32dbb5cb379edfa1a7334
LinuxLinux Kernel2.6.12.1 up to, but not including, 4.14.324; 4.15 up to, but not including, 4.19.293; 4.20 up to, but not including, 5.4.255; 5.5 up to, but not including, 5.10.192; 5.11 up to, but not including, 5.15.123; 5.16 up to, but not including, 6.1.42; 6.2 up to, but not including, 6.4.7; 2.6.124.14.324, 4.19.293, 5.4.255, 5.10.192, 5.15.123, 6.1.42

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Validation of Array Index

The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.

How developers prevent this class of flaw

  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, Ada allows the programmer to constrain the values of a variable and languages such as Java and Ruby will allow the programmer to handle exceptions when an out-of-bounds index is accessed.
  • Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND.

More Improper Validation of Array Index vulnerabilities (CWE-129)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Improper Validation of Array Index vulnerabilities

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