Merge pull request 'Apply Dirty Frag fixes' (#37) from metalefty/raspberrypi:a9 into a9

Reviewed-on: rpms/raspberrypi2#37
This commit is contained in:
Koichiro Iwao 2026-05-08 13:05:37 +00:00
commit 7e436cbe54
3 changed files with 155 additions and 1 deletions

View File

@ -0,0 +1,77 @@
From: Andrew Lukoshko <alukoshko@almalinux.org>
Subject: [PATCH AlmaLinux 10] xfrm: esp: avoid in-place decrypt on shared skb frags
Direct cherry-pick of upstream commit f4c50a4034e6 for AlmaLinux 10
(6.12 kernel).
Verified to apply with `patch -p1 -F0` (no offset, no fuzz, no rejects)
against kernel-6.12.0-124.55.1.el10_1.
ESP-in-UDP packets built from MSG_SPLICE_PAGES (pipe pages) look like
ordinary uncloned nonlinear skbs to ESP input, which takes the no-COW
fast path and decrypts in place over data that is not owned privately
by the skb. Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG
matching TCP, and make ESP input fall back to skb_cow_data() when the
flag is present.
Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
Fixes: 7da0dde68486 ("ip, udp: Support MSG_SPLICE_PAGES")
Fixes: 6d8192bd69bb ("ip6, udp6: Support MSG_SPLICE_PAGES")
(cherry picked from commit f4c50a4034e62ab75f1d5cdd191dd5f9c77fdff4)
Signed-off-by: Andrew Lukoshko <alukoshko@almalinux.org>
---
net/ipv4/esp4.c | 3 ++-
net/ipv4/ip_output.c | 2 ++
net/ipv6/esp6.c | 3 ++-
net/ipv6/ip6_output.c | 2 ++
4 files changed, 8 insertions(+), 2 deletions(-)
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -908,7 +908,8 @@
nfrags = 1;
goto skip_cow;
- } else if (!skb_has_frag_list(skb)) {
+ } else if (!skb_has_frag_list(skb) &&
+ !skb_has_shared_frag(skb)) {
nfrags = skb_shinfo(skb)->nr_frags;
nfrags++;
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1236,6 +1236,8 @@
if (err < 0)
goto error;
copy = err;
+ if (!(flags & MSG_NO_SHARED_FRAGS))
+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
wmem_alloc_delta += copy;
} else if (!zc) {
int i = skb_shinfo(skb)->nr_frags;
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -950,7 +950,8 @@
nfrags = 1;
goto skip_cow;
- } else if (!skb_has_frag_list(skb)) {
+ } else if (!skb_has_frag_list(skb) &&
+ !skb_has_shared_frag(skb)) {
nfrags = skb_shinfo(skb)->nr_frags;
nfrags++;
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1769,6 +1769,8 @@
if (err < 0)
goto error;
copy = err;
+ if (!(flags & MSG_NO_SHARED_FRAGS))
+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
wmem_alloc_delta += copy;
} else if (!zc) {
int i = skb_shinfo(skb)->nr_frags;
--
2.43.0

View File

@ -0,0 +1,68 @@
From: Andrew Lukoshko <alukoshko@almalinux.org>
Subject: [PATCH AlmaLinux 10] rxrpc: linearize incoming DATA packet when it has paged frags
AlmaLinux-specific backport of the intent of the upstream rxrpc fix
posted at https://lore.kernel.org/all/afKV2zGR6rrelPC7@v4bel/
(sibling to upstream commit f4c50a4034e6 in the ESP/xfrm subsystem).
The upstream patch can not be cherry-picked against this 6.12 tree:
its target lines were introduced by upstream commit d0d5c0cd1e71
("rxrpc: Use skb_unshare() rather than skb_cow_data()") which is not
present here. The age-equivalent code path on AlmaLinux 10 is the
centralized skb_unshare() in net/rxrpc/io_thread.c that is run for
every DATA packet with a non-zero securityIndex before in-place
decryption.
skb_unshare() only handles cloned skbs. An skb that is non-cloned but
carries paged fragments (skb->data_len != 0) — e.g. pages attached via
udp_sendpage() / splice() / MSG_SPLICE_PAGES on a UDP socket carrying
rxrpc traffic — slips through and is decrypted in place over data the
skb does not own privately. With kernel-modules-partner installed
(rxrpc.ko enabled), this is exploitable.
Replace the unconditional skb_unshare() with skb_copy() whenever the
skb is cloned OR carries paged fragments. skb_copy() always returns a
freshly allocated linear skb, so subsequent in-place decryption only
touches kernel-owned memory. The original skb is consumed explicitly
(skb_unshare did this internally via consume_skb()).
Verified to apply with `patch -p1 -F0` (no offset, no fuzz, no
rejects) against kernel-6.12.0-124.55.1.el10_1.
Fixes: cac2661c53f3 ("rxrpc: Use skb_cow_data() in rxrpc_recvmsg_data()")
Signed-off-by: Andrew Lukoshko <alukoshko@almalinux.org>
---
net/rxrpc/io_thread.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
--- a/net/rxrpc/io_thread.c
+++ b/net/rxrpc/io_thread.c
@@ -235,16 +235,18 @@
* decryption.
*/
if (sp->hdr.securityIndex != 0) {
- skb = skb_unshare(skb, GFP_ATOMIC);
- if (!skb) {
- rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare_nomem);
- *_skb = NULL;
- return just_discard;
- }
+ if (skb_cloned(skb) || skb->data_len) {
+ struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
+
+ if (!nskb) {
+ rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare_nomem);
+ return just_discard;
+ }
- if (skb != *_skb) {
rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare);
- *_skb = skb;
+ consume_skb(*_skb);
+ *_skb = nskb;
+ skb = nskb;
rxrpc_new_skb(skb, rxrpc_skb_new_unshared);
sp = rxrpc_skb(skb);
}
--
2.43.0

View File

@ -11,7 +11,7 @@ ExclusiveArch: aarch64
%define local_version v8
%define bcmmodel 2711
%define extra_version 4
%define extra_version 5
# This originally implies Kernel 4.x for RPi 2 and is not appropriate now.
# Be careful to change this not to disturb the seamless package update.
@ -54,6 +54,9 @@ Source2002: kvm_stat.logrotate
# AlmaLinux patches
## CVE-2026-31431
Patch1100: 1100-CVE-2026-31431-crypto-Copy-Fail-fixes.patch
## Dirty Frag
Patch1101: 1101-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
Patch1102: 1102-rxrpc-linearize-paged-frags.patch
BuildRequires: kmod, patch, bash, coreutils, tar
BuildRequires: bzip2, xz, findutils, gzip, m4, perl, perl-Carp, make, diffutils, gawk
@ -234,6 +237,8 @@ glibc package.
%patch -P 100 -p1
%patch -P 101 -p1
%patch -P 1100 -p1
%patch -P 1101 -p1
%patch -P 1102 -p1
perl -p -i -e "s/^EXTRAVERSION.*/EXTRAVERSION = -%{release}/" Makefile
perl -p -i -e "s/^CONFIG_LOCALVERSION=.*/CONFIG_LOCALVERSION=/" arch/%{Arch}/configs/bcm2711_defconfig
perl -p -i -e "s/^CONFIG_LOCALVERSION=.*/CONFIG_LOCALVERSION=/" arch/%{Arch}/configs/bcm2712_defconfig
@ -538,6 +543,10 @@ cp $(ls -1 /boot/config-kernel-*-*|sort -V|tail -1) /boot/config-kernel.inc
%endif
%changelog
* Fri May 08 2026 Koichiro Iwao <meta@almalinux.org> - 6.12.47-20250916.v8.5
- rxrpc: linearize incoming DATA packet when it has paged frags
- xfrm: esp: avoid in-place decrypt on shared skb frags
* Thu Apr 30 2026 Koichiro Iwao <meta@almalinux.org> - 6.12.47-20250916.v8.4
- Update CVE-2026-31431 patch to include more upstream commits