CVE-2021-47636

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Source
https://cve.org/CVERecord?id=CVE-2021-47636
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-47636.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2021-47636
Downstream
Related
Published
2025-02-26T06:37:05Z
Modified
2026-03-13T05:20:50Z
Severity
  • 7.1 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H CVSS Calculator
Summary
[none]
Details

In the Linux kernel, the following vulnerability has been resolved:

ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()

Function ubifs_wbuf_write_nolock() may access buf out of bounds in following process:

ubifs_wbuf_write_nolock(): aligned_len = ALIGN(len, 8); // Assume len = 4089, aligned_len = 4096 if (aligned_len <= wbuf->avail) ... // Not satisfy if (wbuf->used) { ubifs_leb_write() // Fill some data in avail wbuf len -= wbuf->avail; // len is still not 8-bytes aligned aligned_len -= wbuf->avail; } n = aligned_len >> c->max_write_shift; if (n) { n <<= c->max_write_shift; err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); // n > len, read out of bounds less than 8(n-len) bytes }

, which can be catched by KASAN:

BUG: KASAN: slab-out-of-bounds in ecc_sw_hamming_calculate+0x1dc/0x7d0 Read of size 4 at addr ffff888105594ff8 by task kworker/u8:4/128 Workqueue: writeback wb_workfn (flush-ubifs_0_0) Call Trace: kasan_report.cold+0x81/0x165 nand_write_page_swecc+0xa9/0x160 ubifs_leb_write+0xf2/0x1b0 [ubifs] ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs] write_head+0xdc/0x1c0 [ubifs] ubifs_jnl_write_inode+0x627/0x960 [ubifs] wb_workfn+0x8af/0xb80

Function ubifs_wbuf_write_nolock() accepts that parameter 'len' is not 8 bytes aligned, the 'len' represents the true length of buf (which is allocated in 'ubifs_jnl_xxx', eg. ubifs_jnl_write_inode), so ubifs_wbuf_write_nolock() must handle the length read from 'buf' carefully to write leb safely.

Fetch a reproducer in [Link].

References

Affected packages

Git /

Affected ranges

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-47636.json"
unresolved_ranges 
[
    {
        "events": [
            {
                "introduced": "2.6.27"
            },
            {
                "fixed": "4.19.238"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "4.20"
            },
            {
                "fixed": "5.4.189"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "5.5"
            },
            {
                "fixed": "5.10.110"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "5.11"
            },
            {
                "fixed": "5.15.33"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "5.16"
            },
            {
                "fixed": "5.16.19"
            }
        ]
    },
    {
        "events": [
            {
                "introduced": "5.17"
            },
            {
                "fixed": "5.17.2"
            }
        ]
    }
]