Описание
In the Linux kernel, the following vulnerability has been resolved: ipvs: fix ipv4 null-ptr-deref in route error path The IPv4 code path in __ip_vs_get_out_rt() calls dst_link_failure() without ensuring skb->dev is set, leading to a NULL pointer dereference in fib_compute_spec_dst() when ipv4_link_failure() attempts to send ICMP destination unreachable messages. The issue emerged after commit ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure") started calling __ip_options_compile() from ipv4_link_failure(). This code path eventually calls fib_compute_spec_dst() which dereferences skb->dev. An attempt was made to fix the NULL skb->dev dereference in commit 0113d9c9d1cc ("ipv4: fix null-deref in ipv4_link_failure"), but it only addressed the immediate dev_net(skb->dev) dereference by using a fallback device. The fix was incomplete because fib_compute_spec_dst() later in the call chain still accesses skb->dev directly, which remains NULL when IPVS calls dst_link_failure(). The crash occurs when:
- IPVS processes a packet in NAT mode with a misconfigured destination
- Route lookup fails in __ip_vs_get_out_rt() before establishing a route
- The error path calls dst_link_failure(skb) with skb->dev == NULL
- ipv4_link_failure() → ipv4_send_dest_unreach() → __ip_options_compile() → fib_compute_spec_dst()
- fib_compute_spec_dst() dereferences NULL skb->dev Apply the same fix used for IPv6 in commit 326bf17ea5d4 ("ipvs: fix ipv6 route unreach panic"): set skb->dev from skb_dst(skb)->dev before calling dst_link_failure(). KASAN: null-ptr-deref in range [0x0000000000000328-0x000000000000032f] CPU: 1 PID: 12732 Comm: syz.1.3469 Not tainted 6.6.114 #2 RIP: 0010:__in_dev_get_rcu include/linux/inetdevice.h:233 RIP: 0010:fib_compute_spec_dst+0x17a/0x9f0 net/ipv4/fib_frontend.c:285 Call Trace:
spec_dst_fill net/ipv4/ip_options.c:232
spec_dst_fill net/ipv4/ip_options.c:229
__ip_options_compile+0x13a1/0x17d0 net/ipv4/ip_options.c:330
ipv4_send_dest_unreach net/ipv4/route.c:1252
ipv4_link_failure+0x702/0xb80 net/ipv4/route.c:1265
dst_link_failure include/net/dst.h:437
__ip_vs_get_out_rt+0x15fd/0x19e0 net/netfilter/ipvs/ip_vs_xmit.c:412
ip_vs_nat_xmit+0x1d8/0xc80 net/netfilter/ipvs/ip_vs_xmit.c:764
A NULL pointer dereference vulnerability was found in the Linux kernel's IPVS (IP Virtual Server) implementation. In __ip_vs_get_out_rt(), when route lookup fails, dst_link_failure() is called with skb->dev set to NULL. The subsequent call chain through ipv4_link_failure() to fib_compute_spec_dst() dereferences skb->dev, causing a kernel crash when IPVS processes packets in NAT mode with a misconfigured destination.
Отчет
This vulnerability affects systems using IPVS for load balancing with NAT mode. The crash occurs when route lookup fails before establishing a route, typically due to misconfiguration. The issue was discovered by KASAN and syzkaller. Prior partial fixes addressed some NULL dereferences but not all code paths.
Меры по смягчению последствий
To mitigate this issue, prevent the ip_vs module from being loaded if IPVS load balancing functionality is not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Affected | ||
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 9 | kernel | Affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected |
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Дополнительная информация
Статус:
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: ipvs: fix ipv4 null-ptr-deref in route error path The IPv4 code path in __ip_vs_get_out_rt() calls dst_link_failure() without ensuring skb->dev is set, leading to a NULL pointer dereference in fib_compute_spec_dst() when ipv4_link_failure() attempts to send ICMP destination unreachable messages. The issue emerged after commit ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure") started calling __ip_options_compile() from ipv4_link_failure(). This code path eventually calls fib_compute_spec_dst() which dereferences skb->dev. An attempt was made to fix the NULL skb->dev dereference in commit 0113d9c9d1cc ("ipv4: fix null-deref in ipv4_link_failure"), but it only addressed the immediate dev_net(skb->dev) dereference by using a fallback device. The fix was incomplete because fib_compute_spec_dst() later in the call chain still accesses skb->dev directly, which remains NULL when IPVS calls dst_link_failure()....
In the Linux kernel, the following vulnerability has been resolved: ipvs: fix ipv4 null-ptr-deref in route error path The IPv4 code path in __ip_vs_get_out_rt() calls dst_link_failure() without ensuring skb->dev is set, leading to a NULL pointer dereference in fib_compute_spec_dst() when ipv4_link_failure() attempts to send ICMP destination unreachable messages. The issue emerged after commit ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure") started calling __ip_options_compile() from ipv4_link_failure(). This code path eventually calls fib_compute_spec_dst() which dereferences skb->dev. An attempt was made to fix the NULL skb->dev dereference in commit 0113d9c9d1cc ("ipv4: fix null-deref in ipv4_link_failure"), but it only addressed the immediate dev_net(skb->dev) dereference by using a fallback device. The fix was incomplete because fib_compute_spec_dst() later in the call chain still accesses skb->dev directly, which remains NULL when IPVS calls dst_link_failure().
In the Linux kernel, the following vulnerability has been resolved: i ...
In the Linux kernel, the following vulnerability has been resolved: ipvs: fix ipv4 null-ptr-deref in route error path The IPv4 code path in __ip_vs_get_out_rt() calls dst_link_failure() without ensuring skb->dev is set, leading to a NULL pointer dereference in fib_compute_spec_dst() when ipv4_link_failure() attempts to send ICMP destination unreachable messages. The issue emerged after commit ed0de45a1008 ("ipv4: recompile ip options in ipv4_link_failure") started calling __ip_options_compile() from ipv4_link_failure(). This code path eventually calls fib_compute_spec_dst() which dereferences skb->dev. An attempt was made to fix the NULL skb->dev dereference in commit 0113d9c9d1cc ("ipv4: fix null-deref in ipv4_link_failure"), but it only addressed the immediate dev_net(skb->dev) dereference by using a fallback device. The fix was incomplete because fib_compute_spec_dst() later in the call chain still accesses skb->dev directly, which remains NULL when IPVS calls dst_link_failure...
Security update for the Linux Kernel (Live Patch 8 for SUSE Linux Enterprise 15 SP7)
5.5 Medium
CVSS3