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Bump version to 6.12.0-211.7.4

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Refresh the dirtyfrag backport to upstream v5 and add the cifs.spnego
hardening patch.

  1103-net-skbuff-propagate-shared-frag-marker.patch
    Refreshed from upstream v3 to v5
    (https://lore.kernel.org/all/ageeJfJHwgzmKXbh@v4bel/). The v5
    series adds three hunks on top of v3: two skb_segment() sites
    (fold frag_skb-> flags into nskb on the per-iteration flag merge;
    fill the marker again when the inner switch rebinds frag_skb on
    head_skb-frags exhaustion) and one tcp_clone_payload() site
    (carry the marker when building an MTU probe skb from sk_write_queue
    frag descriptors). skb_try_coalesce() hunk is retained as in v3/v4
    because the upstream commit that dropped it (f84eca581739) is only
    partially backported in 6.12 -- its skb_split() half is present,
    but the skb_try_coalesce() half is missing.

  1105-smb-client-reject-userspace-cifs.spnego-descriptions.patch
    Upstream commit 3da1fdf4efbc verbatim. Refuses userspace-created
    cifs.spnego keys via request_key(2)/add_key(2); only kernel CIFS
    using the private spnego_cred may create them. cifs.upcall
    treats the key description as kernel-originating
    pid/uid/creduid/upcall_target -- without this fence, userspace
    can spoof those fields.

All five patches verified to apply with patch -p1 -F0 against the
6.12.0-211.7.1.el10_2 source tree (no fuzz, no rejects).
This commit is contained in:
Andrew Lukoshko 2026-05-28 11:55:58 +00:00
parent ab18269911
commit b3c4cf07f6
3 changed files with 169 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

145
1103-net-skbuff-propagate-shared-frag-marker.patch
View File

@ -1,19 +1,25 @@
From: Eduard Abdullin <eabdullin@almalinux.org>
From: Andrew Lukoshko <alukoshko@almalinux.org>
Subject: [PATCH AlmaLinux 10] net: skbuff: propagate shared-frag marker through frag-transfer helpers
Backport of upstream v3 patch posted at
https://lore.kernel.org/all/agW4vC0r8QOUKtRT@v4bel/
Backport of upstream v5 patch posted at
https://lore.kernel.org/all/ageeJfJHwgzmKXbh@v4bel/
(sibling to upstream commit f4c50a4034e6 "xfrm: esp: avoid in-place
decrypt on shared skb frags", already part of 6.12.0-124.56.1 via the
c10s import).
decrypt on shared skb frags").
Three frag-transfer helpers (__pskb_copy_fclone(), skb_try_coalesce(),
and skb_shift()) and the GRO accumulator helpers (skb_gro_receive()
and skb_gro_receive_list()) fail to propagate the SKBFL_SHARED_FRAG
bit in skb_shinfo()->flags when moving frag descriptors from source
to destination. As a result, the destination skb keeps a reference
to the same externally-owned or page-cache-backed pages while
reporting skb_has_shared_frag() as false.
Three frag-transfer helpers in net/core/skbuff.c
(__pskb_copy_fclone(), skb_try_coalesce(), skb_shift()) and the two
GRO accumulator helpers in net/core/gro.c (skb_gro_receive() and
skb_gro_receive_list()) fail to propagate the SKBFL_SHARED_FRAG bit
in skb_shinfo()->flags when moving frag descriptors from source to
destination. In addition, skb_segment() folds only head_skb's flag
into nskb on the per-iteration flag merge, and the inner switch that
rebinds frag_skb to list_skb on head_skb-frags exhaustion does not
fold the new frag_skb's flag into nskb. Finally,
tcp_clone_payload() builds an MTU probe skb by moving frag
descriptors from sk_write_queue skbs into a fresh nskb without
propagating the marker. As a result, 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
@ -39,20 +45,75 @@ skb_segment() reads only skb_shinfo(p)->flags, and skb_segment_list()
reuses each sub-skb's shinfo as the nskb -- both p and lp must carry
the marker.
skb_try_coalesce() hunk: upstream v5 drops the v3/v4 skb_try_coalesce()
change because commit f84eca581739 ("net: account for SKBFL_SHARED_FRAG
in skb_split() and skb_try_coalesce()") covers that site there. Only
the skb_split() half of f84eca581739 is currently backported in 6.12,
so the skb_try_coalesce() hunk is retained here to close the same gap.
Fixes: cef401de7be8 ("net: fix possible wrong checksum generation")
Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags")
Reported-by: Sultan Alsawaf <sultan@kerneltoast.com>
Reported-by: William Bowling <vakzz@zellic.io>
Reported-by: Hyunwoo Kim <imv4bel@gmail.com>
Signed-off-by: Eduard Abdullin <eabdullin@almalinux.org>
Signed-off-by: Andrew Lukoshko <alukoshko@almalinux.org>
---
net/core/gro.c | 4 ++++
net/core/skbuff.c | 5 +++++
2 files changed, 9 insertions(+)
net/core/gro.c | 4 ++++
net/core/skbuff.c | 14 +++++++++++++-
net/ipv4/tcp_output.c | 1 +
3 files changed, 18 insertions(+), 1 deletion(-)
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -213,10 +213,12 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
--- a/net/core/skbuff.c 2026-05-28 13:12:16.410047140 +0200
+++ b/net/core/skbuff.c 2026-05-28 13:17:15.081411917 +0200
@@ -2123,6 +2123,7 @@
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)) {
@@ -4198,6 +4199,8 @@
tgt->ip_summed = CHECKSUM_PARTIAL;
skb->ip_summed = CHECKSUM_PARTIAL;
+ skb_shinfo(tgt)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
+
skb_len_add(skb, -shiftlen);
skb_len_add(tgt, shiftlen);
@@ -4808,7 +4811,8 @@
skb_copy_from_linear_data_offset(head_skb, offset,
skb_put(nskb, hsize), hsize);
- skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
+ skb_shinfo(nskb)->flags |= (skb_shinfo(head_skb)->flags |
+ skb_shinfo(frag_skb)->flags) &
SKBFL_SHARED_FRAG;
if (skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
@@ -4825,6 +4829,9 @@
nfrags = skb_shinfo(list_skb)->nr_frags;
frag = skb_shinfo(list_skb)->frags;
frag_skb = list_skb;
+
+ skb_shinfo(nskb)->flags |= skb_shinfo(frag_skb)->flags & SKBFL_SHARED_FRAG;
+
if (!skb_headlen(list_skb)) {
BUG_ON(!nfrags);
} else {
@@ -6030,6 +6037,8 @@
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;
--- a/net/core/gro.c 2026-05-28 13:12:16.409094447 +0200
+++ b/net/core/gro.c 2026-05-28 13:15:11.599892601 +0200
@@ -214,10 +214,12 @@
p->data_len += len;
p->truesize += delta_truesize;
p->len += len;
@ -65,42 +126,22 @@ Signed-off-by: Eduard Abdullin <eabdullin@almalinux.org>
}
NAPI_GRO_CB(skb)->same_flow = 1;
return 0;
@@ -244,6 +246,8 @@ int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
@@ -245,6 +247,8 @@
p->truesize += skb->truesize;
p->len += skb->len;
+ skb_shinfo(p)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
+
NAPI_GRO_CB(skb)->same_flow = 1;
return 0;
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2123,6 +2123,7 @@ 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)) {
@@ -4198,6 +4199,8 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
tgt->ip_summed = CHECKSUM_PARTIAL;
skb->ip_summed = CHECKSUM_PARTIAL;
+ skb_shinfo(tgt)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
+
skb_len_add(skb, -shiftlen);
skb_len_add(tgt, shiftlen);
@@ -6028,6 +6031,8 @@ 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
--- a/net/ipv4/tcp_output.c 2026-05-28 13:12:16.846070054 +0200
+++ b/net/ipv4/tcp_output.c 2026-05-28 13:14:19.646400034 +0200
@@ -2380,6 +2380,7 @@
todo = min_t(int, skb_frag_size(fragfrom),
probe_size - len);
len += todo;
+ skb_shinfo(to)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
if (lastfrag &&
skb_frag_page(fragfrom) == skb_frag_page(lastfrag) &&
skb_frag_off(fragfrom) == skb_frag_off(lastfrag) +

66
1105-smb-client-reject-userspace-cifs.spnego-descriptions.patch Normal file
View File

@ -0,0 +1,66 @@
From 3da1fdf4efbc490041eb4f836bf596201203f8f2 Mon Sep 17 00:00:00 2001
From: Asim Viladi Oglu Manizada <manizada@pm.me>
Date: Sat, 16 May 2026 21:15:39 +0000
Subject: smb: client: reject userspace cifs.spnego descriptions
cifs.spnego key descriptions contain authority-bearing fields such as
pid, uid, creduid, and upcall_target that cifs.upcall treats as
kernel-originating inputs. However, userspace can also create keys of
this type through request_key(2) or add_key(2), allowing those fields to
be supplied without CIFS origin.
Only accept cifs.spnego descriptions while CIFS is using its private
spnego_cred to request the key.
Fixes: f1d662a7d5e5 ("[CIFS] Add upcall files for cifs to use spnego/kerberos")
Assisted-by: avom-custom-harness:gpt-5.5-qwen3.6-mod-mix
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Asim Viladi Oglu Manizada <manizada@pm.me>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
fs/smb/client/cifs_spnego.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/fs/smb/client/cifs_spnego.c b/fs/smb/client/cifs_spnego.c
index 3a41bbada04c76..44c40727568042 100644
--- a/fs/smb/client/cifs_spnego.c
+++ b/fs/smb/client/cifs_spnego.c
@@ -8,6 +8,7 @@
*/
#include <linux/list.h>
+#include <linux/cred.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <keys/user-type.h>
@@ -40,12 +41,27 @@ cifs_spnego_key_destroy(struct key *key)
kfree(key->payload.data[0]);
}
+static int
+cifs_spnego_key_vet_description(const char *description)
+{
+ /*
+ * cifs.spnego descriptions are authority-bearing inputs to cifs.upcall.
+ * They are only valid when produced by CIFS while using the private
+ * spnego_cred installed below. Do not let userspace create this type
+ * of key through request_key(2)/add_key(2), since the helper treats
+ * pid/uid/creduid/upcall_target as kernel-originating fields.
+ */
+ if (current_cred() != spnego_cred)
+ return -EPERM;
+ return 0;
+}
/*
* keytype for CIFS spnego keys
*/
struct key_type cifs_spnego_key_type = {
.name = "cifs.spnego",
+ .vet_description = cifs_spnego_key_vet_description,
.instantiate = cifs_spnego_key_instantiate,
.destroy = cifs_spnego_key_destroy,
.describe = user_describe,
--
cgit 1.3-korg

11
kernel.spec
View File

@ -182,7 +182,7 @@ Summary: The Linux kernel
# This is needed to do merge window version magic
%define patchlevel 12
# This allows pkg_release to have configurable %%{?dist} tag
%define specrelease 211.7.3%{?buildid}%{?dist}
%define specrelease 211.7.4%{?buildid}%{?dist}
# This defines the kabi tarball version
%define kabiversion 6.12.0-211.7.1.el10_2
@ -1143,6 +1143,7 @@ Patch1101: 1101-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
Patch1102: 1102-rxrpc-linearize-paged-frags.patch
Patch1103: 1103-net-skbuff-propagate-shared-frag-marker.patch
Patch1104: 1104-ptrace-require-cap-on-mm-less-task.patch
Patch1105: 1105-smb-client-reject-userspace-cifs.spnego-descriptions.patch
# END OF PATCH DEFINITIONS
@ -2008,6 +2009,7 @@ ApplyPatch 1101-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
ApplyPatch 1102-rxrpc-linearize-paged-frags.patch
ApplyPatch 1103-net-skbuff-propagate-shared-frag-marker.patch
ApplyPatch 1104-ptrace-require-cap-on-mm-less-task.patch
ApplyPatch 1105-smb-client-reject-userspace-cifs.spnego-descriptions.patch
%{log_msg "End of patch applications"}
# END OF PATCH APPLICATIONS
@ -4514,6 +4516,13 @@ fi\
#
#
%changelog
* Thu May 28 2026 Andrew Lukoshko <alukoshko@almalinux.org> - 6.12.0-211.7.4
- net: skbuff: propagate shared-frag marker through frag-transfer helpers
(refresh to upstream v5: now also covers skb_segment() and
tcp_clone_payload(); CVE-2026-46300 "Fragnesia")
- smb: client: reject userspace cifs.spnego descriptions (upstream commit
3da1fdf4efbc)
* Tue May 19 2026 Andrew Lukoshko <alukoshko@almalinux.org> - 6.12.0-211.7.3
- xfrm: esp: avoid in-place decrypt on shared skb frags (CVE-2026-43284)
- rxrpc: linearize incoming DATA packet when it has paged frags (CVE-2026-43500)