[PATCH OLK-6.6 0/2] net: Fix CVE-2026-23204
Fix CVE-2026-23204 Eric Dumazet (2): net: add skb_header_pointer_careful() helper net/sched: cls_u32: use skb_header_pointer_careful() include/linux/skbuff.h | 12 ++++++++++++ net/sched/cls_u32.c | 13 ++++++------- 2 files changed, 18 insertions(+), 7 deletions(-) -- 2.25.1
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From: Eric Dumazet <edumazet@google.com> stable inclusion from stable-v6.6.124 commit fcbda653b5a888338ce7cdc186ec53edc260fe39 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/13760 CVE: CVE-2026-23204 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 13e00fdc9236bd4d0bff4109d2983171fbcb74c4 ] This variant of skb_header_pointer() should be used in contexts where @offset argument is user-controlled and could be negative. Negative offsets are supported, as long as the zone starts between skb->head and skb->data. Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20260128141539.3404400-2-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: cabd1a976375 ("net/sched: cls_u32: use skb_header_pointer_careful()") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- include/linux/skbuff.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index d64d4fc21166..91c58cfa0e35 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -4113,6 +4113,18 @@ skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer) skb_headlen(skb), buffer); } +/* Variant of skb_header_pointer() where @offset is user-controlled + * and potentially negative. + */ +static inline void * __must_check +skb_header_pointer_careful(const struct sk_buff *skb, int offset, + int len, void *buffer) +{ + if (unlikely(offset < 0 && -offset > skb_headroom(skb))) + return NULL; + return skb_header_pointer(skb, offset, len, buffer); +} + static inline void * __must_check skb_pointer_if_linear(const struct sk_buff *skb, int offset, int len) { -- 2.25.1
From: Eric Dumazet <edumazet@google.com> stable inclusion from stable-v6.6.124 commit 13336a6239b9d7c6e61483017bb8bdfe3ceb10a5 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/13760 CVE: CVE-2026-23204 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit cabd1a976375780dabab888784e356f574bbaed8 ] skb_header_pointer() does not fully validate negative @offset values. Use skb_header_pointer_careful() instead. GangMin Kim provided a report and a repro fooling u32_classify(): BUG: KASAN: slab-out-of-bounds in u32_classify+0x1180/0x11b0 net/sched/cls_u32.c:221 Fixes: fbc2e7d9cf49 ("cls_u32: use skb_header_pointer() to dereference data safely") Reported-by: GangMin Kim <km.kim1503@gmail.com> Closes: https://lore.kernel.org/netdev/CANn89iJkyUZ=mAzLzC4GdcAgLuPnUoivdLaOs6B9rq5_... Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20260128141539.3404400-3-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/sched/cls_u32.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 67f27be13848..1338d9b4c03a 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -161,10 +161,8 @@ TC_INDIRECT_SCOPE int u32_classify(struct sk_buff *skb, int toff = off + key->off + (off2 & key->offmask); __be32 *data, hdata; - if (skb_headroom(skb) + toff > INT_MAX) - goto out; - - data = skb_header_pointer(skb, toff, 4, &hdata); + data = skb_header_pointer_careful(skb, toff, 4, + &hdata); if (!data) goto out; if ((*data ^ key->val) & key->mask) { @@ -214,8 +212,9 @@ TC_INDIRECT_SCOPE int u32_classify(struct sk_buff *skb, if (ht->divisor) { __be32 *data, hdata; - data = skb_header_pointer(skb, off + n->sel.hoff, 4, - &hdata); + data = skb_header_pointer_careful(skb, + off + n->sel.hoff, + 4, &hdata); if (!data) goto out; sel = ht->divisor & u32_hash_fold(*data, &n->sel, @@ -229,7 +228,7 @@ TC_INDIRECT_SCOPE int u32_classify(struct sk_buff *skb, if (n->sel.flags & TC_U32_VAROFFSET) { __be16 *data, hdata; - data = skb_header_pointer(skb, + data = skb_header_pointer_careful(skb, off + n->sel.offoff, 2, &hdata); if (!data) -- 2.25.1
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