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Bump version to 5.14.0-611.54.4

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net: skbuff: propagate shared-frag marker through pskb_copy()

Sibling fix to the xfrm/esp shared-frag patch shipped in 611.54.2.
__pskb_copy_fclone() and skb_try_coalesce() shallow-copied frag
descriptors without propagating SKBFL_SHARED_FRAG, so destinations
referencing externally-owned pages reported skb_has_shared_frag()
as false. Combined with an nft 'dup to <local>' rule (or any other
nf_dup_ipv4 / xt_TEE caller), this lets an unprivileged user write
into the page cache of a root-owned read-only file via ESP-input
in-place decryption.

Backport of https://lore.kernel.org/all/agRfuVOeMI5pbHhY@v4bel/
This commit is contained in:
Andrew Lukoshko 2026-05-13 13:18:28 +00:00 committed by Andrew Lukoshko
parent d62b1833b9
commit b0ff80e02d
2 changed files with 72 additions and 2 deletions
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65
SOURCES/1102-net-skbuff-propagate-shared-frag-marker.patch Normal file
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@ -0,0 +1,65 @@
From: Andrew Lukoshko <alukoshko@almalinux.org>
Subject: [PATCH AlmaLinux 9] net: skbuff: propagate shared-frag marker through pskb_copy()
Backport of upstream patch posted at
https://lore.kernel.org/all/agRfuVOeMI5pbHhY@v4bel/
(sibling to the xfrm/esp shared-frag fix already shipped as
1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch in
5.14.0-611.54.2).
__pskb_copy_fclone() shallow-copies the source's frag descriptors and
bumps each page's refcount via skb_frag_ref(), then defers the rest
of the shinfo metadata to skb_copy_header(). That helper only carries
over gso_{size,segs,type} and never touches skb_shinfo()->flags, so
the destination skb keeps a reference to the same externally-owned or
page-cache-backed pages while reporting skb_has_shared_frag() as
false.
The mismatch is harmful in any in-place writer that uses
skb_has_shared_frag() to decide whether shared pages must be detoured
through skb_cow_data(). ESP input is one such writer (esp4.c,
esp6.c), and a single nft 'dup to <local>' rule -- or any other
nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d
skb in esp_input() with the marker stripped, letting an unprivileged
user write into the page cache of a root-owned read-only file via
authencesn-ESN stray writes.
Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors
were actually moved from the source. skb_copy() and skb_copy_expand()
share skb_copy_header() too but linearize all paged data into freshly
allocated head storage and emerge with nr_frags == 0, so
skb_has_shared_frag() returns false on its own; they need no change.
Verified to apply with `patch -p1 -F0` (no offset, no fuzz, no rejects)
against kernel-5.14.0-611.54.1.el9_7.
Fixes: cef401de7be8 ("net: fix possible wrong checksum generation")
Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags")
Reported-by: William Bowling <vakzz@zellic.io>
Reported-by: Hyunwoo Kim <imv4bel@gmail.com>
Signed-off-by: Andrew Lukoshko <alukoshko@almalinux.org>
---
net/core/skbuff.c | 3 +++
1 file changed, 3 insertions(+)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2026,6 +2026,7 @@ struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
skb_frag_ref(skb, i);
}
skb_shinfo(n)->nr_frags = i;
+ skb_shinfo(n)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
}
if (skb_has_frag_list(skb)) {
@@ -5740,6 +5741,8 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
from_shinfo->frags,
from_shinfo->nr_frags * sizeof(skb_frag_t));
to_shinfo->nr_frags += from_shinfo->nr_frags;
+ if (from_shinfo->nr_frags)
+ to_shinfo->flags |= from_shinfo->flags & SKBFL_SHARED_FRAG;
if (!skb_cloned(from))
from_shinfo->nr_frags = 0;
--
2.43.0

9
SPECS/kernel.spec
View File

@ -165,13 +165,13 @@ Summary: The Linux kernel
# define buildid .local
%define specversion 5.14.0
%define patchversion 5.14
%define pkgrelease 611.54.3
%define pkgrelease 611.54.4
%define kversion 5
%define tarfile_release 5.14.0-611.54.1.el9_7
# This is needed to do merge window version magic
%define patchlevel 14
# This allows pkg_release to have configurable %%{?dist} tag
%define specrelease 611.54.3%{?buildid}%{?dist}
%define specrelease 611.54.4%{?buildid}%{?dist}
# This defines the kabi tarball version
%define kabiversion 5.14.0-611.54.1.el9_7
@ -958,6 +958,7 @@ Patch2006: 0006-Bring-back-deprecated-pci-ids-to-qla4xxx-driver.patch
Patch2007: 0007-Bring-back-deprecated-pci-ids-to-be2iscsi-driver.patch
Patch1100: 1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
Patch1101: 1101-rxrpc-linearize-paged-frags.patch
Patch1102: 1102-net-skbuff-propagate-shared-frag-marker.patch
Patch11111: ppc64le-kvm-support.patch
@ -1704,6 +1705,7 @@ ApplyPatch 0006-Bring-back-deprecated-pci-ids-to-qla4xxx-driver.patch
ApplyPatch 0007-Bring-back-deprecated-pci-ids-to-be2iscsi-driver.patch
ApplyPatch 1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
ApplyPatch 1101-rxrpc-linearize-paged-frags.patch
ApplyPatch 1102-net-skbuff-propagate-shared-frag-marker.patch
# END OF PATCH APPLICATIONS
@ -3775,6 +3777,9 @@ fi
#
#
%changelog
* Wed May 13 2026 Andrew Lukoshko <alukoshko@almalinux.org> - 5.14.0-611.54.4
- net: skbuff: propagate shared-frag marker through pskb_copy()
* Thu May 07 2026 Andrew Lukoshko <alukoshko@almalinux.org> - 5.14.0-611.54.3
- rxrpc: linearize incoming DATA packet when it has paged frags