Bug 2334541 (CVE-2024-56638) - CVE-2024-56638 kernel: netfilter: nft_inner: incorrect percpu area handling under softirq
Summary: CVE-2024-56638 kernel: netfilter: nft_inner: incorrect percpu area handling u...
Keywords:
Status: NEW
Alias: CVE-2024-56638
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2024-12-27 16:02 UTC by OSIDB Bzimport
Modified: 2025-02-12 08:00 UTC (History)
4 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2024-12-27 16:02:20 UTC
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_inner: incorrect percpu area handling under softirq

Softirq can interrupt ongoing packet from process context that is
walking over the percpu area that contains inner header offsets.

Disable bh and perform three checks before restoring the percpu inner
header offsets to validate that the percpu area is valid for this
skbuff:

1) If the NFT_PKTINFO_INNER_FULL flag is set on, then this skbuff
   has already been parsed before for inner header fetching to
   register.

2) Validate that the percpu area refers to this skbuff using the
   skbuff pointer as a cookie. If there is a cookie mismatch, then
   this skbuff needs to be parsed again.

3) Finally, validate if the percpu area refers to this tunnel type.

Only after these three checks the percpu area is restored to a on-stack
copy and bh is enabled again.

After inner header fetching, the on-stack copy is stored back to the
percpu area.

Comment 1 Avinash Hanwate 2024-12-28 03:07:55 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024122735-CVE-2024-56638-3a3d@gregkh/T


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