CVE-2021-47636 Affecting kernel-bootwrapper package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-CENTOS6-KERNELBOOTWRAPPER-9005791
- published1 Mar 2025
- disclosed26 Feb 2025
Introduced: 26 Feb 2025
NewCVE-2021-47636 (opens in a new tab)How to fix?
There is no fixed version for Centos:6 kernel-bootwrapper.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-bootwrapper package and not the kernel-bootwrapper package as distributed by Centos.
See How to fix? for Centos:6 relevant fixed versions and status.
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].
References
- https://access.redhat.com/security/cve/CVE-2021-47636
- https://git.kernel.org/stable/c/07a209fadee7b53b46858538e1177597273862e4
- https://git.kernel.org/stable/c/3b7fb89135a20587d57f8877c02e25003e9edbdf
- https://git.kernel.org/stable/c/4f2262a334641e05f645364d5ade1f565c85f20b
- https://git.kernel.org/stable/c/5343575aa11c5d7044107d59d43f84aec01312b0
- https://git.kernel.org/stable/c/a7054aaf1909cf40489c0ec1b728fdcf79c751a6
- https://git.kernel.org/stable/c/b80ccbec0e4804436c382d7dd60e943c386ed83a
- https://git.kernel.org/stable/c/e09fa5318d51f522e1af4fbaf8f74999355980c8