net: skbuff: propagate shared-frag marker in skb_zerocopy()
skb_zerocopy() moves frag descriptors from @from into @to and takes a
reference on each frag, but it does not copy skb_shinfo(from)->flags into
skb_shinfo(to)->flags. A destination skb holding the same page-cache
backed frags as the source therefore reports skb_has_shared_frag() as
false.
That breaks the invariant relied on by later in-place writers. ESP input
checks skb_has_shared_frag() before deciding whether an uncloned
nonlinear skb can skip skb_cow_data(); with the marker lost, an skb that
skb_zerocopy() built for nfnetlink_queue or for an openvswitch upcall is
decrypted in place, letting an unprivileged user write into the page
cache of a root-owned read-only file.
Propagate SKBFL_SHARED_FRAG when frag descriptors are copied, as done for
the other frag-transfer helpers.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
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Sat, 07 Nov 2026 22:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-269 |
Sat, 07 Nov 2026 22:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux linux
|
|
| Vendors & Products |
Linux linux
|
Sat, 07 Nov 2026 20:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: net: skbuff: propagate shared-frag marker in skb_zerocopy() skb_zerocopy() moves frag descriptors from @from into @to and takes a reference on each frag, but it does not copy skb_shinfo(from)->flags into skb_shinfo(to)->flags. A destination skb holding the same page-cache backed frags as the source therefore reports skb_has_shared_frag() as false. That breaks the invariant relied on by later in-place writers. ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(); with the marker lost, an skb that skb_zerocopy() built for nfnetlink_queue or for an openvswitch upcall is decrypted in place, letting an unprivileged user write into the page cache of a root-owned read-only file. Propagate SKBFL_SHARED_FRAG when frag descriptors are copied, as done for the other frag-transfer helpers. | |
| Title | net: skbuff: propagate shared-frag marker in skb_zerocopy() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-11-07T20:40:33.661Z
Reserved: 2026-09-25T10:25:14.405Z
Link: CVE-2026-99284
No data.
Status : Received
Published: 2026-11-07T21:17:00.603
Modified: 2026-11-07T21:17:00.603
Link: CVE-2026-99284
No data.
OpenCVE Enrichment
Updated: 2026-11-07T22:30:12Z
-
CWE-269
Improper Privilege Management