Bug 2559747 (CVE-2026-99030) - CVE-2026-99030 kernel: net: skbuff: don't leave stale bytes in skb_copy_and_csum_bits()
Summary: CVE-2026-99030 kernel: net: skbuff: don't leave stale bytes in skb_copy_and_c...
Keywords:
Status: NEW
Alias: CVE-2026-99030
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-10-23 13:29 UTC by OSIDB Bzimport
Modified: 2026-10-27 12:57 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


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Description OSIDB Bzimport 2026-10-23 13:29:31 UTC
In the Linux kernel, the following vulnerability has been resolved:

net: skbuff: don't leave stale bytes in skb_copy_and_csum_bits()

When skb_copy_and_csum_bits() reaches unreadable frags it returns 0
after copying only the linear part, and the rest of the caller's buffer
is left as it was.  The callers copy into a buffer that is about to go
out on the wire: an ICMP error quoting the offending packet, or a
driver's TX bounce buffer in skb_copy_and_csum_dev().  Neither buffer
is zeroed beforehand, so whatever was in memory there gets sent.

Zero the part of the buffer we didn't fill.  The checksum usually
won't match the data any more, so the receiver will usually drop the
packet, but either way it no longer carries anything it shouldn't.
Only zero for a positive @len, a negative one from a broken caller must
not turn into a huge memset().


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