From 7df722cfc38c000b58e15e922fcc96e3eb8c80c8 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Sat, 23 May 2026 13:20:31 +0200 Subject: [PATCH] 6.1-stable patches added patches: net-skbuff-preserve-shared-frag-marker-during-coalescing.patch net-skbuff-propagate-shared-frag-marker-through-frag-transfer-helpers.patch series --- ...shared-frag-marker-during-coalescing.patch | 48 ++++++ ...marker-through-frag-transfer-helpers.patch | 146 ++++++++++++++++++ queue-6.1/series | 2 + 3 files changed, 196 insertions(+) create mode 100644 queue-6.1/net-skbuff-preserve-shared-frag-marker-during-coalescing.patch create mode 100644 queue-6.1/net-skbuff-propagate-shared-frag-marker-through-frag-transfer-helpers.patch create mode 100644 queue-6.1/series diff --git a/queue-6.1/net-skbuff-preserve-shared-frag-marker-during-coalescing.patch b/queue-6.1/net-skbuff-preserve-shared-frag-marker-during-coalescing.patch new file mode 100644 index 0000000000..541f6e35aa --- /dev/null +++ b/queue-6.1/net-skbuff-preserve-shared-frag-marker-during-coalescing.patch @@ -0,0 +1,48 @@ +From f84eca5817390257cef78013d0112481c503b4a3 Mon Sep 17 00:00:00 2001 +From: William Bowling +Date: Wed, 13 May 2026 04:16:35 +0000 +Subject: net: skbuff: preserve shared-frag marker during coalescing + +From: William Bowling + +commit f84eca5817390257cef78013d0112481c503b4a3 upstream. + +skb_try_coalesce() can attach paged frags from @from to @to. If @from +has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same +externally-owned or page-cache-backed frags, but the shared-frag marker +is currently lost. + +That breaks the invariant relied on by later in-place writers. In +particular, ESP input checks skb_has_shared_frag() before deciding +whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP +receive coalescing has moved shared frags into an unmarked skb, ESP can +see skb_has_shared_frag() as false and decrypt in place over page-cache +backed frags. + +Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged +frags. The tailroom copy path does not need the marker because it copies +bytes into @to's linear data rather than transferring frag descriptors. + +Fixes: cef401de7be8 ("net: fix possible wrong checksum generation") +Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags") +Signed-off-by: William Bowling +Reviewed-by: Eric Dumazet +Tested-by: Jiayuan Chen +Link: https://patch.msgid.link/20260513041635.1289541-1-vakzz@zellic.io +Signed-off-by: Jakub Kicinski +Signed-off-by: Greg Kroah-Hartman +--- + net/core/skbuff.c | 2 ++ + 1 file changed, 2 insertions(+) + +--- a/net/core/skbuff.c ++++ b/net/core/skbuff.c +@@ -5512,6 +5512,8 @@ bool skb_try_coalesce(struct sk_buff *to + 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; diff --git a/queue-6.1/net-skbuff-propagate-shared-frag-marker-through-frag-transfer-helpers.patch b/queue-6.1/net-skbuff-propagate-shared-frag-marker-through-frag-transfer-helpers.patch new file mode 100644 index 0000000000..6b9058ab41 --- /dev/null +++ b/queue-6.1/net-skbuff-propagate-shared-frag-marker-through-frag-transfer-helpers.patch @@ -0,0 +1,146 @@ +From 48f6a5356a33dd78e7144ae1faef95ffc990aae0 Mon Sep 17 00:00:00 2001 +From: Hyunwoo Kim +Date: Sat, 16 May 2026 07:28:53 +0900 +Subject: net: skbuff: propagate shared-frag marker through frag-transfer helpers + +From: Hyunwoo Kim + +commit 48f6a5356a33dd78e7144ae1faef95ffc990aae0 upstream. + +Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail +to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when +moving frags from source to destination. __pskb_copy_fclone() defers +the rest of the shinfo metadata to skb_copy_header() after copying +frag descriptors, but that helper only carries over gso_{size,segs, +type} and never touches skb_shinfo()->flags; skb_shift() moves frag +descriptors directly and leaves flags untouched. 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 +through skb_cow_data(). ESP input is one such writer (esp4.c, +esp6.c), and a single nft 'dup to ' 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. + +The same omission exists in skb_gro_receive() and skb_gro_receive_list(). +The former moves the incoming skb's frag descriptors into the +accumulator's last sub-skb via two paths (a direct frag-move loop and +the head_frag + memcpy path); the latter chains the incoming skb whole +onto p's frag_list. Downstream 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. + +The same omission also exists in tcp_clone_payload(), which builds an +MTU probe skb by moving frag descriptors from skbs on sk_write_queue +into a freshly allocated nskb. The helper falls into the same family +and warrants the same fix for consistency; no TCP TX-side in-place +writer is currently known to reach a user page through this gap, but +a future consumer depending on the marker would regress silently. + +The same omission exists in skb_segment(): the per-iteration flag +merge takes only head_skb's flag, 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. Fold frag_skb's flag at both sites +so segments drawing frags from frag_list members carry the marker. + +Fixes: cef401de7be8 ("net: fix possible wrong checksum generation") +Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags") +Suggested-by: Sabrina Dubroca +Suggested-by: Sultan Alsawaf +Suggested-by: Ben Hutchings +Suggested-by: Lin Ma +Suggested-by: Jingguo Tan +Suggested-by: Aaron Esau +Cc: stable@vger.kernel.org +Signed-off-by: Hyunwoo Kim +Tested-by: Rajat Gupta +Link: https://patch.msgid.link/ageeJfJHwgzmKXbh@v4bel +Signed-off-by: Paolo Abeni +[bwh: Backported to 6.1: + - skb_gro_receive_list() is in net/ipv4/udp_offload.c here + - Drop change to tcp_clone_payload(), which does not exist here +] +Signed-off-by: Ben Hutchings +Signed-off-by: Greg Kroah-Hartman +--- + net/core/gro.c | 2 ++ + net/core/skbuff.c | 9 ++++++++- + net/ipv4/udp_offload.c | 2 ++ + 3 files changed, 12 insertions(+), 1 deletion(-) + +--- a/net/core/gro.c ++++ b/net/core/gro.c +@@ -281,10 +281,12 @@ done: + p->data_len += len; + p->truesize += delta_truesize; + p->len += len; ++ skb_shinfo(p)->flags |= skbinfo->flags & SKBFL_SHARED_FRAG; + if (lp != p) { + lp->data_len += len; + lp->truesize += delta_truesize; + lp->len += len; ++ skb_shinfo(lp)->flags |= skbinfo->flags & SKBFL_SHARED_FRAG; + } + NAPI_GRO_CB(skb)->same_flow = 1; + return 0; +--- a/net/core/skbuff.c ++++ b/net/core/skbuff.c +@@ -1798,6 +1798,7 @@ struct sk_buff *__pskb_copy_fclone(struc + 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)) { +@@ -3789,6 +3790,8 @@ onlymerged: + 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); + +@@ -4362,7 +4365,8 @@ normal: + 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)) +@@ -4379,6 +4383,9 @@ normal: + 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 { +--- a/net/ipv4/udp_offload.c ++++ b/net/ipv4/udp_offload.c +@@ -546,6 +546,8 @@ static int skb_gro_receive_list(struct s + 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; diff --git a/queue-6.1/series b/queue-6.1/series new file mode 100644 index 0000000000..e76af69f9f --- /dev/null +++ b/queue-6.1/series @@ -0,0 +1,2 @@ +net-skbuff-preserve-shared-frag-marker-during-coalescing.patch +net-skbuff-propagate-shared-frag-marker-through-frag-transfer-helpers.patch -- 2.47.3