# CVE-2024-49885: mm, slub: avoid zeroing kmalloc redzone > A kernel bug causes memory corruption and system crashes when specific debug and initialization options are enabled. - **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 21 Oct 2024 - **Updated:** 21 Oct 2026 - **Also known as:** AZL-52969, BELL-CVE-2024-49885, DEBIAN-CVE-2024-49885, GHSA-2h93-g5hm-9qcv, UBUNTU-CVE-2024-49885 ## What is CVE-2024-49885? CVE-2024-49885 is a medium-severity memory corruption vulnerability in Linux kernel, published on 21 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: mm, slub: avoid zeroing kmalloc redzone Since commit 946fa0dbf2d8 ("mm/slub: extend redzone check to extra allocated kmalloc space than requested"), setting orig_size treats the wasted space (object_size - orig_size) as a redzone. However with init_on_free=1 we clear the full object->size, including the redzone. Additionally we clear the object metadata, including the stored orig_size, making it zero, which makes check_object() treat the whole object as a redzone. These issues lead to the following BUG report with "slub_debug=FUZ init_on_free=1": [ 0.000000] ============================================================================= [ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten [ 0.000000] ----------------------------------------------------------------------------- [ 0.000000] [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc [ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc [ 0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) [ 0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 [ 0.000000] [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........ [ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc ........ [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc ........ [ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............ [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 [ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT) [ 0.000000] Call trace: [ 0.000000] dump_backtrace+0x90/0xe8 [ 0.000000] show_stack+0x18/0x24 [ 0.000000] dump_stack_lvl+0x74/0x8c [ 0.000000] dump_stack+0x18/0x24 [ 0.000000] print_trailer+0x150/0x218 [ 0.000000] check_object+0xe4/0x454 [ 0.000000] free_to_partial_list+0x2f8/0x5ec To address the issue, use orig_size to clear the used area. And restore the value of orig_size after clear the remaining area. When CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns s->object_size. So when using memset to init the area, the size can simply be orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not enabled. And orig_size can never be bigger than object_size. ## Which versions are affected by CVE-2024-49885? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2024-49885? Apply the vendor's patch. ## Is CVE-2024-49885 being exploited? There is no known exploitation of CVE-2024-49885 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2024-49885 and fix it if it is affected. What it is: CVE-2024-49885 is a medium-severity memory corruption vulnerability in Linux kernel, published on 21 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2024-49885 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2024-49885/ (Markdown: https://insights.sbomify.com/CVE-2024-49885/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2024-49885 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-49885 - OSV: https://osv.dev/vulnerability/CVE-2024-49885 --- From sbomify Insights: https://insights.sbomify.com/CVE-2024-49885/ Summaries are generated and may contain mistakes; the official description above is the record.