diff options
| author | Weiming Shi <bestswngs@gmail.com> | 2026-03-18 21:06:01 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-25 11:13:29 +0100 |
| commit | 1e4e2f5e48cec0cccaea9815fb9486c084ba41e2 (patch) | |
| tree | 0829fa54b80c9fc78301236d00a577b41447cb2b /net/ipv4 | |
| parent | 993afb7edc86e9dc4c0087b8d3c96cdbd6c3a5e2 (diff) | |
icmp: fix NULL pointer dereference in icmp_tag_validation()
[ Upstream commit 614aefe56af8e13331e50220c936fc0689cf5675 ]
icmp_tag_validation() unconditionally dereferences the result of
rcu_dereference(inet_protos[proto]) without checking for NULL.
The inet_protos[] array is sparse -- only about 15 of 256 protocol
numbers have registered handlers. When ip_no_pmtu_disc is set to 3
(hardened PMTU mode) and the kernel receives an ICMP Fragmentation
Needed error with a quoted inner IP header containing an unregistered
protocol number, the NULL dereference causes a kernel panic in
softirq context.
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143)
Call Trace:
<IRQ>
icmp_rcv (net/ipv4/icmp.c:1527)
ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207)
ip_local_deliver_finish (net/ipv4/ip_input.c:242)
ip_local_deliver (net/ipv4/ip_input.c:262)
ip_rcv (net/ipv4/ip_input.c:573)
__netif_receive_skb_one_core (net/core/dev.c:6164)
process_backlog (net/core/dev.c:6628)
handle_softirqs (kernel/softirq.c:561)
</IRQ>
Add a NULL check before accessing icmp_strict_tag_validation. If the
protocol has no registered handler, return false since it cannot
perform strict tag validation.
Fixes: 8ed1dc44d3e9 ("ipv4: introduce hardened ip_no_pmtu_disc mode")
Reported-by: Xiang Mei <xmei5@asu.edu>
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
Link: https://patch.msgid.link/20260318130558.1050247-4-bestswngs@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/icmp.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 471dd862f663..e619b73f5063 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -1067,10 +1067,12 @@ out: static bool icmp_tag_validation(int proto) { + const struct net_protocol *ipprot; bool ok; rcu_read_lock(); - ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; + ipprot = rcu_dereference(inet_protos[proto]); + ok = ipprot ? ipprot->icmp_strict_tag_validation : false; rcu_read_unlock(); return ok; } |