kernel/linux.git/net/ipv6/exthdrs.c, branch v6.18.41

ipv6: exthdrs: refresh nh after handling HAO option

2026-06-09T10:28:40+00:00

commit f7b52afe3592eae66e160586b45a3f2242972c63 upstream. ip6_parse_tlv() caches skb_network_header(skb) in nh while walking IPv6 TLVs. ipv6_dest_hao() may call pskb_expand_head() for a cloned skb, which can move the skb head and invalidate the cached network header pointer. Refresh nh after ipv6_dest_hao() returns so any trailing padding or TLVs are parsed from the current skb head. This matches the existing pattern used in ip6_parse_tlv() after helpers that can modify skb header storage. Fixes: a831f5bbc89a ("[IPV6] MIP6: Add inbound interface of home address option.") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Xin Liu Co-developed-by: Luxing Yin Signed-off-by: Luxing Yin Signed-off-by: Zhengchuan Liang Signed-off-by: Ren Wei Reviewed-by: Justin Iurman Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/7aba1debc2196189172499e5769802b026f8caf8.1779247873.git.zcliangcn@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()

2026-06-09T10:28:40+00:00

commit d47548a36639095939f4747d4c43f2271366f565 upstream. ipv6_hop_jumbo() calls pskb_trim_rcsum(), which can change skb pointers. Let's recompute nh pointer to make sure any change won't mess things up. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Justin Iurman Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260522112013.12342-1-justin.iurman@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()

2026-06-09T10:28:30+00:00

[ Upstream commit 9d5e7a46a9f6d8f503b41bfefef70659845f1679 ] ipv6_rpl_srh_decompress() computes: outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3); hdrlen is __u8. For n >= 127 the result exceeds 255 and silently truncates. With n=127 (cmpri=15, cmpre=15, pad=0, hdrlen=16): (128 * 16) >> 3 = 256, truncated to 0 as __u8 The caller in ipv6_rpl_srh_rcv() then places the compressed header at buf + ((ohdr->hdrlen + 1) << 3). With hdrlen=0 this is buf + 8, but the decompressed region occupies buf[0..2055] (8-byte header plus 128 full addresses). The compressed header overlaps the decompressed data, and ipv6_rpl_srh_compress() writes into this overlap, corrupting the routing header of the forwarded packet. The existing guard at exthdrs.c:546 checks (n + 1) > 255, which prevents n+1 from overflowing unsigned char (the segments_left field), but does not prevent the computed hdrlen from overflowing __u8. n=127 passes because 128 <= 255, yet hdrlen=256 does not fit. Tighten the bound to (n + 1) > 127. This caps n at 126, giving hdrlen = (127 * 16) >> 3 = 254, which fits in __u8. The compressed header then lands at buf + ((254 + 1) << 3) = buf + 2040, exactly past the decompressed region (buf[0..2039]). No overlap. 127 segments is well beyond any realistic RPL deployment. Fixes: 8610c7c6e3bd ("net: ipv6: add support for rpl sr exthdr") Signed-off-by: Rahul Chandelkar Link: https://patch.msgid.link/20260525154031.2290876-1-rc@rexion.ai Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: ioam: add NULL check for idev in ipv6_hop_ioam()

2026-06-01T15:50:44+00:00

commit d4ea0dfd75011b78cebf3808f98ac4c4f51a6fb9 upstream. Reported by Sashiko: The function ipv6_hop_ioam() accesses __in6_dev_get(skb->dev)->cnf.ioam6_enabled without validating the returned idev pointer. Because addrconf_ifdown() can concurrently clear dev->ip6_ptr via RCU, __in6_dev_get() can return NULL during interface teardown, which could cause a NULL pointer dereference when processing an IOAM Hop-by-Hop option. Let's add a check and use SKB_DROP_REASON_IPV6DISABLED accordingly. Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace") Cc: stable@vger.kernel.org Signed-off-by: Justin Iurman Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260517183059.29140-1-justin.iurman@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: ioam: refresh hdr pointer before ioam6_event()

2026-06-01T15:50:41+00:00

commit e46e6bc97fb1f339730ff1ba74267fbf48e7a422 upstream. Reported by Sashiko: In ipv6_hop_ioam(), the hdr pointer is initialized to point into the skb's linear data buffer. Later, the code calls skb_ensure_writable(), which might reallocate the buffer: if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len)) goto drop; /* Trace pointer may have changed */ trace = (struct ioam6_trace_hdr *)(skb_network_header(skb) + optoff + sizeof(*hdr)); ioam6_fill_trace_data(skb, ns, trace, true); ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev), GFP_ATOMIC, (void *)trace, hdr->opt_len - 2); If the skb is cloned or lacks sufficient linear headroom, skb_ensure_writable() will invoke pskb_expand_head(), which reallocates the skb's data buffer and frees the old one, invalidating pointers to it. While the code recalculates the trace pointer immediately after the call to skb_ensure_writable(), it fails to recalculate the hdr pointer. This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF. Fixes: f655c78d6225 ("net: exthdrs: ioam6: send trace event") Cc: stable@vger.kernel.org Signed-off-by: Justin Iurman Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260520124242.32320-1-justin.iurman@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: rpl: reserve mac_len headroom when recompressed SRH grows

2026-05-07T04:12:02+00:00

commit 9e6bf146b55999a095bb14f73a843942456d1adc upstream. ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards. Fixes: 8610c7c6e3bd ("net: ipv6: add support for rpl sr exthdr") Cc: stable Reported-by: Anthropic Signed-off-by: Greg Kroah-Hartman Link: https://patch.msgid.link/2026042133-gout-unvented-1bd9@gregkh Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: add NULL checks for idev in SRv6 paths

2026-04-27T13:27:27+00:00

[ Upstream commit 06413793526251870e20402c39930804f14d59c0 ] __in6_dev_get() can return NULL when the device has no IPv6 configuration (e.g. MTU < IPV6_MIN_MTU or after NETDEV_UNREGISTER). Add NULL checks for idev returned by __in6_dev_get() in both seg6_hmac_validate_skb() and ipv6_srh_rcv() to prevent potential NULL pointer dereferences. Fixes: 1ababeba4a21 ("ipv6: implement dataplane support for rthdr type 4 (Segment Routing Header)") Fixes: bf355b8d2c30 ("ipv6: sr: add core files for SR HMAC support") Signed-off-by: Minhong He Reviewed-by: Andrea Mayer Link: https://patch.msgid.link/20260316073301.106643-1-heminhong@kylinos.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()

2026-03-04T12:21:30+00:00

[ Upstream commit 6db8b56eed62baacaf37486e83378a72635c04cc ] On the receive path, __ioam6_fill_trace_data() uses trace->nodelen to decide how much data to write for each node. It trusts this field as-is from the incoming packet, with no consistency check against trace->type (the 24-bit field that tells which data items are present). A crafted packet can set nodelen=0 while setting type bits 0-21, causing the function to write ~100 bytes past the allocated region (into skb_shared_info), which corrupts adjacent heap memory and leads to a kernel panic. Add a shared helper ioam6_trace_compute_nodelen() in ioam6.c to derive the expected nodelen from the type field, and use it: - in ioam6_iptunnel.c (send path, existing validation) to replace the open-coded computation; - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose nodelen is inconsistent with the type field, before any data is written. Per RFC 9197, bits 12-21 are each short (4-octet) fields, so they are included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to 0xff1ffc00). Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace") Cc: stable@vger.kernel.org Signed-off-by: Junxi Qian Reviewed-by: Justin Iurman Link: https://patch.msgid.link/20260211040412.86195-1-qjx1298677004@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: exthdrs: annotate data-race over multiple sysctl

2026-03-04T12:20:17+00:00

[ Upstream commit 978b67d28358b0b4eacfa94453d1ad4e09b123ad ] Following four sysctls can change under us, add missing READ_ONCE(). - ipv6.sysctl.max_dst_opts_len - ipv6.sysctl.max_dst_opts_cnt - ipv6.sysctl.max_hbh_opts_len - ipv6.sysctl.max_hbh_opts_cnt Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260115094141.3124990-8-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: annotate data-races around devconf->rpl_seg_enabled

2025-09-03T00:01:06+00:00

devconf->rpl_seg_enabled can be changed concurrently from /proc/sys/net/ipv6/conf, annotate lockless reads on it. Signed-off-by: Yue Haibing Link: https://patch.msgid.link/20250901123726.1972881-2-yuehaibing@huawei.com Signed-off-by: Jakub Kicinski