CVE-2021-47656— jffs2: fix use-after-free in jffs2_clear_xattr_subsystem
Affected Version Matrix 20
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| 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 | |||
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I. Basic Information for CVE-2021-47656
Vulnerability Information
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Vulnerability Title
jffs2: fix use-after-free in jffs2_clear_xattr_subsystem
Source: NVD (National Vulnerability Database)
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: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
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
II. Public POCs for CVE-2021-47656
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|---|
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Patches & Fixes for CVE-2021-47656 (9)
Same Patch Batch · Linux · 2025-02-26 · 706 CVEs total
| CVE-2022-49498 | ALSA: pcm: Check for null pointer of pointer substream before dereferencing it | |
| CVE-2022-49486 | ASoC: fsl: Fix refcount leak in imx_sgtl5000_probe | |
| CVE-2022-49488 | drm/msm/mdp5: Return error code in mdp5_mixer_release when deadlock is detected | |
| CVE-2022-49489 | drm/msm/disp/dpu1: set vbif hw config to NULL to avoid use after memory free during pm run | |
| CVE-2022-49490 | drm/msm/mdp5: Return error code in mdp5_pipe_release when deadlock is detected | |
| CVE-2022-49491 | drm/rockchip: vop: fix possible null-ptr-deref in vop_bind() | |
| CVE-2022-49492 | nvme-pci: fix a NULL pointer dereference in nvme_alloc_admin_tags | |
| CVE-2022-49493 | ASoC: rt5645: Fix errorenous cleanup order | |
| CVE-2022-49494 | mtd: rawnand: cadence: fix possible null-ptr-deref in cadence_nand_dt_probe() | |
| CVE-2022-49495 | drm/msm/hdmi: check return value after calling platform_get_resource_byname() | |
| CVE-2022-49497 | net: remove two BUG() from skb_checksum_help() | |
| CVE-2022-49496 | media: mediatek: vcodec: prevent kernel crash when rmmod mtk-vcodec-dec.ko | |
| CVE-2022-49502 | media: rga: fix possible memory leak in rga_probe | |
| CVE-2022-49507 | regulator: da9121: Fix uninit-value in da9121_assign_chip_model() | |
| CVE-2022-49508 | HID: elan: Fix potential double free in elan_input_configured | |
| CVE-2022-49506 | drm/mediatek: Add vblank register/unregister callback functions | |
| CVE-2022-49504 | scsi: lpfc: Inhibit aborts if external loopback plug is inserted | |
| CVE-2022-49505 | NFC: NULL out the dev->rfkill to prevent UAF | |
| CVE-2022-49501 | usbnet: Run unregister_netdev() before unbind() again | |
| CVE-2022-49500 | wl1251: dynamically allocate memory used for DMA |
Showing top 20 of 706 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Linux
- CVE-2026-46300
net: skbuff: preserve shared-frag marker during coalescing - CVE-2026-43503
net: skbuff: propagate shared-frag marker through frag-trans - CVE-2026-43502
net/rds: handle zerocopy send cleanup before the message is - CVE-2026-43501
ipv6: rpl: reserve mac_len headroom when recompressed SRH gr - CVE-2026-43498
accel/ivpu: Disallow re-exporting imported GEM objects
Same vendor: Linux
- CVE-2026-46300
net: skbuff: preserve shared-frag marker during coalescing - CVE-2026-43503
net: skbuff: propagate shared-frag marker through frag-trans - CVE-2026-43502
net/rds: handle zerocopy send cleanup before the message is - CVE-2026-43501
ipv6: rpl: reserve mac_len headroom when recompressed SRH gr - CVE-2026-43498
accel/ivpu: Disallow re-exporting imported GEM objects
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