CVE-2024-49884

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Source
https://cve.org/CVERecord?id=CVE-2024-49884
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-49884.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2024-49884
Downstream
Related
Published
2024-10-21T18:01:21.517Z
Modified
2026-05-28T03:55:18.142075245Z
Summary
ext4: fix slab-use-after-free in ext4_split_extent_at()
Details

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

ext4: fix slab-use-after-free in ext4splitextent_at()

We hit the following use-after-free:

================================================================== BUG: KASAN: slab-use-after-free in ext4splitextentat+0xba8/0xcc0 Read of size 2 at addr ffff88810548ed08 by task kworker/u20:0/40 CPU: 0 PID: 40 Comm: kworker/u20:0 Not tainted 6.9.0-dirty #724 Call Trace: <TASK> kasanreport+0x93/0xc0 ext4splitextentat+0xba8/0xcc0 ext4splitextent.isra.0+0x18f/0x500 ext4splitconvertextents+0x275/0x750 ext4exthandleunwrittenextents+0x73e/0x1580 ext4extmapblocks+0xe20/0x2dc0 ext4mapblocks+0x724/0x1700 ext4do_writepages+0x12d6/0x2a70 [...]

Allocated by task 40: __kmallocnoprof+0x1ac/0x480 ext4findextent+0xf3b/0x1e70 ext4extmapblocks+0x188/0x2dc0 ext4mapblocks+0x724/0x1700 ext4dowritepages+0x12d6/0x2a70 [...]

Freed by task 40: kfree+0xf1/0x2b0 ext4findextent+0xa71/0x1e70 ext4extinsertextent+0xa22/0x3260 ext4splitextentat+0x3ef/0xcc0 ext4splitextent.isra.0+0x18f/0x500 ext4splitconvertextents+0x275/0x750 ext4exthandleunwrittenextents+0x73e/0x1580 ext4extmapblocks+0xe20/0x2dc0 ext4mapblocks+0x724/0x1700 ext4dowritepages+0x12d6/0x2a70

[...]

The flow of issue triggering is as follows:

ext4splitextentat path = *ppath ext4extinsertextent(ppath) ext4extcreatenewleaf(ppath) ext4findextent(origpath) path = *origpath readextenttreeblock // return -ENOMEM or -EIO ext4freeextpath(path) kfree(path) *origpath = NULL a. If err is -ENOMEM: ext4extdirty(path + path->pdepth) // path use-after-free !!! b. If err is -EIO and we have EXTDEBUG defined: ext4extshowleaf(path) eh = path[depth].p_hdr // path also use-after-free !!!

So when trying to zeroout or fix the extent length, call ext4findextent() to update the path.

In addition we use *ppath directly as an ext4extshowleaf() input to avoid possible use-after-free when EXTDEBUG is defined, and to avoid unnecessary path updates.

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/49xxx/CVE-2024-49884.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
dfe5080939ea4686b3414b5d970a9b26733c57a4
Fixed
393a46f60ea4f249dc9d496d4eb2d542f5e11ade
Fixed
448100a29395b0c8b4c42967155849fe0fbe808f
Fixed
e52f933598b781d291b9297e39c463536da0e185
Fixed
cafcc1bd62934547c76abf46c6d0d54f135006fe
Fixed
a5401d4c3e2a3d25643c567d26e6de327774a2c9
Fixed
8fe117790b37c84c651e2bad9efc0e7fda73c0e3
Fixed
5d949ea75bb529ea6342e83465938a3b0ac51238
Fixed
915ac3630488af0ca194dc63b86d99802b4f6e18
Fixed
c26ab35702f8cd0cdc78f96aa5856bfb77be798f

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-49884.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
3.18.0
Fixed
4.19.323
Type
ECOSYSTEM
Events
Introduced
4.20.0
Fixed
5.4.290
Type
ECOSYSTEM
Events
Introduced
5.5.0
Fixed
5.10.227
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.168
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.113
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.55
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.10.14
Type
ECOSYSTEM
Events
Introduced
6.11.0
Fixed
6.11.3

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-49884.json"