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CVE-2021-47636— ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ubifs_wbuf_write_nolock函数中的越界读取。

CVSS 7.1 · High EPSS 0.25% · P16

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< 5343575aa11c5d7044107d59d43f84aec01312b0 affected
1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< b80ccbec0e4804436c382d7dd60e943c386ed83a affected
1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< 07a209fadee7b53b46858538e1177597273862e4 affected
1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< a7054aaf1909cf40489c0ec1b728fdcf79c751a6 affected
1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< e09fa5318d51f522e1af4fbaf8f74999355980c8 affected
1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< 3b7fb89135a20587d57f8877c02e25003e9edbdf affected
1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d< 4f2262a334641e05f645364d5ade1f565c85f20b affected
2.6.27 affected
… +8 more rows
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I. Basic Information for CVE-2021-47636

Vulnerability Information
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Vulnerability Title
ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()
Source: CVE Program / CVE List V5
Vulnerability 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].
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于ubifs_wbuf_write_nolock函数中的越界读取。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1e51764a3c2ac05a23a22b2a95ddee4d9bffb16d ~ 5343575aa11c5d7044107d59d43f84aec01312b0 -
Linux Linux 2.6.27 -

II. Public POCs for CVE-2021-47636

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III. Intelligence Information for CVE-2021-47636

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Patches & Fixes for CVE-2021-47636 (7)

Same Patch Batch · Linux · 2025-02-26 · 706 CVEs total

CVE-2022-49149 9.8 CRITICAL rxrpc: Fix call timer start racing with call destruction
CVE-2022-49561 9.8 CRITICAL netfilter: conntrack: re-fetch conntrack after insertion
CVE-2022-49407 9.8 CRITICAL dlm: fix plock invalid read
CVE-2022-49280 9.8 CRITICAL NFSD: prevent underflow in nfssvc_decode_writeargs()
CVE-2022-49201 9.8 CRITICAL ibmvnic: fix race between xmit and reset
CVE-2022-49194 9.8 CRITICAL net: bcmgenet: Use stronger register read/writes to assure ordering
CVE-2022-49093 9.8 CRITICAL skbuff: fix coalescing for page_pool fragment recycling
CVE-2022-49094 9.8 CRITICAL net/tls: fix slab-out-of-bounds bug in decrypt_internal
CVE-2022-49260 9.8 CRITICAL crypto: hisilicon/sec - fix the aead software fallback for engine
CVE-2022-49418 9.8 CRITICAL NFSv4: Fix free of uninitialized nfs4_label on referral lookup.
CVE-2022-49362 9.8 CRITICAL NFSD: Fix potential use-after-free in nfsd_file_put()
CVE-2022-49356 9.8 CRITICAL SUNRPC: Trap RDMA segment overflows
CVE-2022-49058 9.1 CRITICAL cifs: potential buffer overflow in handling symlinks
CVE-2022-49114 8.8 HIGH scsi: libfc: Fix use after free in fc_exch_abts_resp()
CVE-2022-49535 8.8 HIGH scsi: lpfc: Fix null pointer dereference after failing to issue FLOGI and PLOGI
CVE-2022-49238 8.8 HIGH ath11k: free peer for station when disconnect from AP for QCA6390/WCN6855
CVE-2022-49479 8.8 HIGH mt76: fix tx status related use-after-free race on station removal
CVE-2022-49138 8.8 HIGH Bluetooth: hci_event: Ignore multiple conn complete events
CVE-2022-49519 8.8 HIGH ath10k: skip ath10k_halt during suspend for driver state RESTARTING
CVE-2022-49470 8.8 HIGH Bluetooth: btmtksdio: fix use-after-free at btmtksdio_recv_event

Showing top 20 of 706 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47636

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