CVE-2021-47636

HIGH EPSS 14.0%
Published Feb 26, 20251y ago · Modified Jun 17, 20262w ago
7.1 CVSS 3.1
High
Find Similar
Published Feb 26, 2025 1y ago
Last Modified Jun 17, 2026 2w ago

Description

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].

CVSS Details

Base Score
7.1
Exploitability
1.8
Impact
5.2
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
14.0% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-125 Out-of-bounds Read Memory Safety

Affected Products 6

VendorProductVersionRange
linuxlinux_kernel*≥2.6.27  –  <4.19.238
linuxlinux_kernel*≥4.20  –  <5.4.189
linuxlinux_kernel*≥5.5  –  <5.10.110
linuxlinux_kernel*≥5.11  –  <5.15.33
linuxlinux_kernel*≥5.16  –  <5.16.19
linuxlinux_kernel*≥5.17  –  <5.17.2

References 7

  • git.kernel.org https://git.kernel.org/stable/c/07a209fadee7b53b46858538e1177597273862e4
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3b7fb89135a20587d57f8877c02e25003e9edbdf
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/4f2262a334641e05f645364d5ade1f565c85f20b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5343575aa11c5d7044107d59d43f84aec01312b0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a7054aaf1909cf40489c0ec1b728fdcf79c751a6
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b80ccbec0e4804436c382d7dd60e943c386ed83a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e09fa5318d51f522e1af4fbaf8f74999355980c8
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/07a209fadee7b53b46858538e1177597273862e4
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3b7fb89135a20587d57f8877c02e25003e9edbdf
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/4f2262a334641e05f645364d5ade1f565c85f20b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5343575aa11c5d7044107d59d43f84aec01312b0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a7054aaf1909cf40489c0ec1b728fdcf79c751a6
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b80ccbec0e4804436c382d7dd60e943c386ed83a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e09fa5318d51f522e1af4fbaf8f74999355980c8
    Patch