CVE-2021-47638

ubifs: rename_whiteout: Fix double free for whiteout_ui->data

Description

In the Linux kernel, the following vulnerability has been resolved: ubifs: rename_whiteout: Fix double free for whiteout_ui->data 'whiteout_ui->data' will be freed twice if space budget fail for rename whiteout operation as following process: rename_whiteout dev = kmalloc whiteout_ui->data = dev kfree(whiteout_ui->data) // Free first time iput(whiteout) ubifs_free_inode kfree(ui->data) // Double free! KASAN reports: ================================================================== BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70 Call Trace: kfree+0x117/0x490 ubifs_free_inode+0x4f/0x70 [ubifs] i_callback+0x30/0x60 rcu_do_batch+0x366/0xac0 __do_softirq+0x133/0x57f Allocated by task 1506: kmem_cache_alloc_trace+0x3c2/0x7a0 do_rename+0x9b7/0x1150 [ubifs] ubifs_rename+0x106/0x1f0 [ubifs] do_syscall_64+0x35/0x80 Freed by task 1506: kfree+0x117/0x490 do_rename.cold+0x53/0x8a [ubifs] ubifs_rename+0x106/0x1f0 [ubifs] do_syscall_64+0x35/0x80 The buggy address belongs to the object at ffff88810238bed8 which belongs to the cache kmalloc-8 of size 8 ================================================================== Let ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused assignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode() -> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it (because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release', and the nlink of whiteout inode is 0).

Category

5.5
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.02%
Affected: Linux Linux
Affected: Linux Linux
Published at:
Updated at:

References

Link Tags
https://git.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274 patch
https://git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa patch
https://git.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fc patch
https://git.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8 patch
https://git.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742 patch
https://git.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f patch
https://git.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123dd patch
https://git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e patch

Frequently Asked Questions

What is the severity of CVE-2021-47638?
CVE-2021-47638 has been scored as a medium severity vulnerability.
How to fix CVE-2021-47638?
To fix CVE-2021-47638, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-47638 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-47638 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-47638?
CVE-2021-47638 affects Linux Linux, Linux Linux.
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