Riskcovery

CVE-2026-93226

ipv6: use RCU iterator to dump route exceptions

State
Published
Severity
Not scored
Published
Sep 24, 2026
Updated
Oct 19, 2026
Reserved
Sep 17, 2026

Read the record on cve.org

Description

In the Linux kernel, the following vulnerability has been resolved:

ipv6: use RCU iterator to dump route exceptions

rt6_nh_dump_exceptions() uses hlist_for_each_entry() to iterate over RCU-protected exception lists. The caller holds rcu_read_lock(), but does not hold rt6_exception_lock, so rt6_insert_exception() can concurrently add an entry with hlist_add_head_rcu().

KCSAN reports this race (irrelevant details omitted):

================================================================== BUG: KCSAN: data-race in rt6_insert_exception / rt6_nh_dump_exceptions

write (marked) to 0xffff8a7c44c59620 of 8 bytes by interrupt on cpu 5: rt6_insert_exception+0x3bb/0x760 __ip6_rt_update_pmtu+0x4fe/0x750 ip6_sk_update_pmtu+0x19a/0x3b0 udpv6_err+0x3ff/0x800 icmpv6_notify+0x1e1/0x440 icmpv6_rcv+0x8c0/0xab0 ip6_protocol_deliver_rcu+0x616/0x840 ip6_input_finish+0xb9/0x160 ... entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8a7c44c59620 of 8 bytes by task 549 on cpu 14: rt6_nh_dump_exceptions+0xb3/0x260 rt6_dump_route+0x53e/0x5f0 fib6_dump_node+0x6d/0xf0 fib6_walk_continue+0x290/0x2d0 fib6_dump_table+0x28d/0x360 inet6_dump_fib+0x37d/0x620 rtnl_dumpit+0x7b/0xd0 netlink_dump+0x3ae/0x7e0 ... entry_SYSCALL_64_after_hwframe+0x77/0x7f

4 locks held by dumper/549: ... #1: (rcu_read_lock){....}-{1:3}, at: inet6_dump_fib+0x88/0x620 #2: (&tb->tb6_lock){+.-.}-{3:3}, at: fib6_dump_table+0x1e9/0x360 #3: (rcu_read_lock){....}-{1:3}, at: rt6_dump_route+0x483/0x5f0

value changed: 0xffff8a7c44e05700 -> 0xffff8a7c45d60100

Reported by Kernel Concurrency Sanitizer on: CPU: 14 UID: 0 PID: 549 Comm: dumper Not tainted 7.2.0-rc7-virtme #38 PREEMPT(lazy) ...

Use hlist_for_each_entry_rcu() to safely iterate over the exception list.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

ProductVersions
LinuxLinux
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before dffbfb3117138e8e0e09d05f507bd36ca1f696e5Affected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before 6bd3f94ed858f2d072627546b4cdf712b0f8ea88Affected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before 9c6be625e1a7258e845d6193b3b6b084a00f8e9eAffected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before 3665abc3d2ae8a78cb67f858e848481432ec75dbAffected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before eda56ee17713f9dd834b922f7dbfa2e25fa6358cAffected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before a602cd128d17a793e12888edc8eda85821ede7e1Affected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before f6b1b15848fd91fe122dac0d19d3d666e35075b6Affected
  • 1e47b4837f3bdaa425727cfe09f5ae3b6c4c41a9 to before 47cdab0d51aaa9bd85f8e4904585bd5bd4df4488Affected
LinuxLinux
  • 5.3Affected
  • before 5.3Not affected
  • 5.10.270 through 5.10.*Not affected
  • 5.15.221 through 5.15.*Not affected
  • 6.1.188 through 6.1.*Not affected
  • 6.6.157 through 6.6.*Not affected
  • 6.12.109 through 6.12.*Not affected
  • 6.18.50 through 6.18.*Not affected
  • 7.2.4 through 7.2.*Not affected
  • 7.3 and laterNot affected

References

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