<p>There is no fixed version for <code>Centos:7</code> <code>kernel-bootwrapper</code>.</p>

Out-of-bounds Read Affecting kernel-bootwrapper package, versions *

Threat Intelligence

0.04% (15^th percentile)

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Snyk ID SNYK-CENTOS7-KERNELBOOTWRAPPER-7761621
published 21 Aug 2024
disclosed 17 Aug 2024

Report a new vulnerability Found a mistake?

Introduced: 17 Aug 2024

CVE-2024-42305 Open this link in a new tab CWE-125 Open this link in a new tab

How to fix?

There is no fixed version for Centos:7 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:7 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

ext4: check dot and dotdot of dx_root before making dir indexed

Syzbot reports a issue as follows:

BUG: unable to handle page fault for address: ffffed11022e24fe PGD 23ffee067 P4D 23ffee067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0 Call Trace: <TASK> make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341 ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451 ext4_rename fs/ext4/namei.c:3936 [inline] ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214 [...]

The immediate cause of this problem is that there is only one valid dentry for the block to be split during do_split, so split==0 results in out of bounds accesses to the map triggering the issue.

do_split
  unsigned split
  dx_make_map
   count = 1
  split = count/2 = 0;
  continued = hash2 == map[split - 1].hash;
   ---&gt; map[4294967295]

The maximum length of a filename is 255 and the minimum block size is 1024, so it is always guaranteed that the number of entries is greater than or equal to 2 when do_split() is called.

But syzbot's crafted image has no dot and dotdot in dir, and the dentry distribution in dirblock is as follows:

bus dentry1 hole dentry2 free |xx--|xx-------------|...............|xx-------------|...............| 0 12 (8+248)=256 268 256 524 (8+256)=264 788 236 1024

So when renaming dentry1 increases its name_len length by 1, neither hole nor free is sufficient to hold the new dentry, and make_indexed_dir() is called.

In make_indexed_dir() it is assumed that the first two entries of the dirblock must be dot and dotdot, so bus and dentry1 are left in dx_root because they are treated as dot and dotdot, and only dentry2 is moved to the new leaf block. That's why count is equal to 1.

Therefore add the ext4_check_dx_root() helper function to add more sanity checks to dot and dotdot before starting the conversion to avoid the above issue.

References

CVSS Scores

version 3.1

Attack Vector (AV)

Local
Attack Complexity (AC)

Low
Privileges Required (PR)

Low
User Interaction (UI)

None

Scope (S)

Unchanged

Confidentiality (C)

High
Integrity (I)

None
Availability (A)

High

Out-of-bounds Read Affecting kernel-bootwrapper package, versions *

Severity

Based on CentOS security rating