Apply Dirty Frag fixes (CVE-2026-43284, CVE-2026-43500)
Apply the same Patch1100 (xfrm/esp) and Patch1101 (rxrpc) shipped on the AlmaLinux 10 main branch. Release is not bumped since 226 has not yet shipped to users; a second changelog entry is added under the existing 6.12.0-226 version.
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77
1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
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77
1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
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@ -0,0 +1,77 @@
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From: Andrew Lukoshko <alukoshko@almalinux.org>
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Subject: [PATCH AlmaLinux 10] xfrm: esp: avoid in-place decrypt on shared skb frags
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Direct cherry-pick of upstream commit f4c50a4034e6 for AlmaLinux 10
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(6.12 kernel).
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Verified to apply with `patch -p1 -F0` (no offset, no fuzz, no rejects)
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against kernel-6.12.0-124.55.1.el10_1.
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ESP-in-UDP packets built from MSG_SPLICE_PAGES (pipe pages) look like
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ordinary uncloned nonlinear skbs to ESP input, which takes the no-COW
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fast path and decrypts in place over data that is not owned privately
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by the skb. Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG
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matching TCP, and make ESP input fall back to skb_cow_data() when the
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flag is present.
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Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
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Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
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Fixes: 7da0dde68486 ("ip, udp: Support MSG_SPLICE_PAGES")
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Fixes: 6d8192bd69bb ("ip6, udp6: Support MSG_SPLICE_PAGES")
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(cherry picked from commit f4c50a4034e62ab75f1d5cdd191dd5f9c77fdff4)
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Signed-off-by: Andrew Lukoshko <alukoshko@almalinux.org>
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---
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net/ipv4/esp4.c | 3 ++-
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net/ipv4/ip_output.c | 2 ++
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net/ipv6/esp6.c | 3 ++-
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net/ipv6/ip6_output.c | 2 ++
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4 files changed, 8 insertions(+), 2 deletions(-)
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--- a/net/ipv4/esp4.c
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+++ b/net/ipv4/esp4.c
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@@ -908,7 +908,8 @@
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nfrags = 1;
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goto skip_cow;
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- } else if (!skb_has_frag_list(skb)) {
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+ } else if (!skb_has_frag_list(skb) &&
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+ !skb_has_shared_frag(skb)) {
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nfrags = skb_shinfo(skb)->nr_frags;
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nfrags++;
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--- a/net/ipv4/ip_output.c
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+++ b/net/ipv4/ip_output.c
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@@ -1236,6 +1236,8 @@
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if (err < 0)
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goto error;
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copy = err;
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+ if (!(flags & MSG_NO_SHARED_FRAGS))
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+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
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wmem_alloc_delta += copy;
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} else if (!zc) {
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int i = skb_shinfo(skb)->nr_frags;
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--- a/net/ipv6/esp6.c
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+++ b/net/ipv6/esp6.c
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@@ -950,7 +950,8 @@
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nfrags = 1;
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goto skip_cow;
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- } else if (!skb_has_frag_list(skb)) {
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+ } else if (!skb_has_frag_list(skb) &&
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+ !skb_has_shared_frag(skb)) {
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nfrags = skb_shinfo(skb)->nr_frags;
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nfrags++;
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--- a/net/ipv6/ip6_output.c
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+++ b/net/ipv6/ip6_output.c
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@@ -1769,6 +1769,8 @@
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if (err < 0)
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goto error;
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copy = err;
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+ if (!(flags & MSG_NO_SHARED_FRAGS))
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+ skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
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wmem_alloc_delta += copy;
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} else if (!zc) {
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int i = skb_shinfo(skb)->nr_frags;
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--
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2.43.0
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69
1101-rxrpc-linearize-paged-frags.patch
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69
1101-rxrpc-linearize-paged-frags.patch
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@ -0,0 +1,69 @@
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From: Andrew Lukoshko <alukoshko@almalinux.org>
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Subject: [PATCH AlmaLinux 10] rxrpc: linearize incoming DATA packet when it has paged frags
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AlmaLinux-specific backport of the intent of the upstream rxrpc fix
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posted at https://lore.kernel.org/all/afKV2zGR6rrelPC7@v4bel/ for the
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"Dirty Frag" class of bugs (sibling to upstream commit f4c50a4034e6 in
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the ESP/xfrm subsystem).
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The upstream patch can not be cherry-picked against this 6.12 tree:
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its target lines were introduced by upstream commit d0d5c0cd1e71
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("rxrpc: Use skb_unshare() rather than skb_cow_data()") which is not
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present here. The age-equivalent code path on AlmaLinux 10 is the
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centralized skb_unshare() in net/rxrpc/io_thread.c that is run for
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every DATA packet with a non-zero securityIndex before in-place
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decryption.
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skb_unshare() only handles cloned skbs. An skb that is non-cloned but
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carries paged fragments (skb->data_len != 0) — e.g. pages attached via
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udp_sendpage() / splice() / MSG_SPLICE_PAGES on a UDP socket carrying
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rxrpc traffic — slips through and is decrypted in place over data the
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skb does not own privately. With kernel-modules-partner installed
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(rxrpc.ko enabled), this is exploitable.
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Replace the unconditional skb_unshare() with skb_copy() whenever the
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skb is cloned OR carries paged fragments. skb_copy() always returns a
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freshly allocated linear skb, so subsequent in-place decryption only
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touches kernel-owned memory. The original skb is consumed explicitly
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(skb_unshare did this internally via consume_skb()).
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Verified to apply with `patch -p1 -F0` (no offset, no fuzz, no
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rejects) against kernel-6.12.0-124.55.1.el10_1.
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Fixes: cac2661c53f3 ("rxrpc: Use skb_cow_data() in rxrpc_recvmsg_data()")
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Signed-off-by: Andrew Lukoshko <alukoshko@almalinux.org>
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---
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net/rxrpc/io_thread.c | 18 ++++++++++--------
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1 file changed, 10 insertions(+), 8 deletions(-)
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--- a/net/rxrpc/io_thread.c
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+++ b/net/rxrpc/io_thread.c
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@@ -235,16 +235,18 @@
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* decryption.
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*/
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if (sp->hdr.securityIndex != 0) {
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- skb = skb_unshare(skb, GFP_ATOMIC);
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- if (!skb) {
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- rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare_nomem);
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- *_skb = NULL;
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- return just_discard;
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- }
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+ if (skb_cloned(skb) || skb->data_len) {
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+ struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
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+
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+ if (!nskb) {
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+ rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare_nomem);
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+ return just_discard;
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+ }
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- if (skb != *_skb) {
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rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare);
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- *_skb = skb;
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+ consume_skb(*_skb);
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+ *_skb = nskb;
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+ skb = nskb;
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rxrpc_new_skb(skb, rxrpc_skb_new_unshared);
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sp = rxrpc_skb(skb);
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}
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--
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2.43.0
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@ -1143,6 +1143,8 @@ Patch2007: 0007-Bring-back-deprecated-pci-ids-to-be2iscsi-driver.patch
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Patch2008: 0008-Bring-back-deprecated-pci-ids-to-megaraid_sas-driver.patch
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Patch2009: 0009-Bring-back-deprecated-pci-ids-to-mpt3sas-driver.patch
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Patch2010: 0001-Keep-fs-btrfs-files-in-modules-package.patch
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Patch1100: 1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
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Patch1101: 1101-rxrpc-linearize-paged-frags.patch
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# END OF PATCH DEFINITIONS
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@ -2038,6 +2040,8 @@ ApplyPatch 0007-Bring-back-deprecated-pci-ids-to-be2iscsi-driver.patch
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ApplyPatch 0008-Bring-back-deprecated-pci-ids-to-megaraid_sas-driver.patch
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ApplyPatch 0009-Bring-back-deprecated-pci-ids-to-mpt3sas-driver.patch
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ApplyPatch 0001-Keep-fs-btrfs-files-in-modules-package.patch
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ApplyPatch 1100-xfrm-esp-avoid-in-place-decrypt-shared-skb-frags.patch
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ApplyPatch 1101-rxrpc-linearize-paged-frags.patch
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%{log_msg "End of patch applications"}
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# END OF PATCH APPLICATIONS
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@ -4552,6 +4556,10 @@ fi\
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#
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#
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%changelog
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* Fri May 08 2026 Andrew Lukoshko <alukoshko@almalinux.org> - 6.12.0-226
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- xfrm: esp: avoid in-place decrypt on shared skb frags
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- rxrpc: linearize incoming DATA packet when it has paged frags
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* Thu May 07 2026 Eduard Abdullin <eabdullin@almalinux.org> - 6.12.0-226
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- Debrand for AlmaLinux OS
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- Use AlmaLinux OS secure boot cert
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