Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2021-47656— jffs2: fix use-after-free in jffs2_clear_xattr_subsystem

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jffs2_clear_xattr_subsystem函数中释放后重用。

CVSS 7.8 · High EPSS 0.25% · P17

Possible ATT&CK Techniques 1 AI

T1055 · Process Injection

Affected Version Matrix 20

VendorProduct Version RangeStatus
Linux Linux aa98d7cf59b5b0764d3502662053489585faf2fe< 9150cb625b46f68d524f4cfd491f1aafc23e10a9 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< 3bd2454162ec6bbb5503233c804fce6e4b6dcec5 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< c3b07c875fa8f906f932976460fd14798596f101 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< 30bf7244acf32f19cb722c39f7bc1c2a9f300422 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< 7bb7428dd73991bf4b3a7a61b493ca50046c2b13 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< 7a75740206af5f17e9f3efa384211cba70213da1 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< 22327bd7988f21de3a53c1373f3b81542bfe1f44 affected
aa98d7cf59b5b0764d3502662053489585faf2fe< 8c0f024f29e055840a5a89fe23b96ae3f921afed affected
… +12 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2021-47656

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
jffs2: fix use-after-free in jffs2_clear_xattr_subsystem
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: jffs2: fix use-after-free in jffs2_clear_xattr_subsystem When we mount a jffs2 image, assume that the first few blocks of the image are normal and contain at least one xattr-related inode, but the next block is abnormal. As a result, an error is returned in jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then called in jffs2_build_filesystem() and then again in jffs2_do_fill_super(). Finally we can observe the following report: ================================================================== BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac Read of size 8 at addr ffff8881243384e0 by task mount/719 Call Trace: dump_stack+0x115/0x16b jffs2_clear_xattr_subsystem+0x95/0x6ac jffs2_do_fill_super+0x84f/0xc30 jffs2_fill_super+0x2ea/0x4c0 mtd_get_sb+0x254/0x400 mtd_get_sb_by_nr+0x4f/0xd0 get_tree_mtd+0x498/0x840 jffs2_get_tree+0x25/0x30 vfs_get_tree+0x8d/0x2e0 path_mount+0x50f/0x1e50 do_mount+0x107/0x130 __se_sys_mount+0x1c5/0x2f0 __x64_sys_mount+0xc7/0x160 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Allocated by task 719: kasan_save_stack+0x23/0x60 __kasan_kmalloc.constprop.0+0x10b/0x120 kasan_slab_alloc+0x12/0x20 kmem_cache_alloc+0x1c0/0x870 jffs2_alloc_xattr_ref+0x2f/0xa0 jffs2_scan_medium.cold+0x3713/0x4794 jffs2_do_mount_fs.cold+0xa7/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] Freed by task 719: kmem_cache_free+0xcc/0x7b0 jffs2_free_xattr_ref+0x78/0x98 jffs2_clear_xattr_subsystem+0xa1/0x6ac jffs2_do_mount_fs.cold+0x5e6/0x2253 jffs2_do_fill_super+0x383/0xc30 jffs2_fill_super+0x2ea/0x4c0 [...] The buggy address belongs to the object at ffff8881243384b8 which belongs to the cache jffs2_xattr_ref of size 48 The buggy address is located 40 bytes inside of 48-byte region [ffff8881243384b8, ffff8881243384e8) [...] ================================================================== The triggering of the BUG is shown in the following stack: ----------------------------------------------------------- jffs2_fill_super jffs2_do_fill_super jffs2_do_mount_fs jffs2_build_filesystem jffs2_scan_medium jffs2_scan_eraseblock <--- ERROR jffs2_clear_xattr_subsystem <--- free jffs2_clear_xattr_subsystem <--- free again ----------------------------------------------------------- An error is returned in jffs2_do_mount_fs(). If the error is returned by jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to be executed. If the error is returned by jffs2_build_filesystem(), the jffs2_clear_xattr_subsystem() also does not need to be executed again. So move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root' to fix this UAF problem.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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jffs2_clear_xattr_subsystem函数中释放后重用。
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 aa98d7cf59b5b0764d3502662053489585faf2fe ~ 9150cb625b46f68d524f4cfd491f1aafc23e10a9 -
Linux Linux 2.6.18 -

II. Public POCs for CVE-2021-47656

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2021-47656

请登录查看更多情报信息。

Patches & Fixes for CVE-2021-47656 (9)

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

CVE-2022-49561 9.8 CRITICAL netfilter: conntrack: re-fetch conntrack after insertion
CVE-2022-49149 9.8 CRITICAL rxrpc: Fix call timer start racing with call destruction
CVE-2022-49356 9.8 CRITICAL SUNRPC: Trap RDMA segment overflows
CVE-2022-49407 9.8 CRITICAL dlm: fix plock invalid read
CVE-2022-49362 9.8 CRITICAL NFSD: Fix potential use-after-free in nfsd_file_put()
CVE-2022-49280 9.8 CRITICAL NFSD: prevent underflow in nfssvc_decode_writeargs()
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-2022-49201 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-2022-49058 9.1 CRITICAL cifs: potential buffer overflow in handling symlinks
CVE-2022-49111 8.8 HIGH Bluetooth: Fix use after free in hci_send_acl
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-2022-49519 8.8 HIGH ath10k: skip ath10k_halt during suspend for driver state RESTARTING
CVE-2022-49138 8.8 HIGH Bluetooth: hci_event: Ignore multiple conn complete events
CVE-2022-49471 8.8 HIGH rtw89: cfo: check mac_id to avoid out-of-bounds
CVE-2022-49159 8.8 HIGH scsi: qla2xxx: Implement ref count for SRB

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-2021-47656

No comments yet

Leave a comment