kernel/linux.git, branch linux-5.10.y

Linux 5.10.263

2026-08-06T17:21:31+00:00

Signed-off-by: Greg Kroah-Hartman

x86/bugs: Make Safe-RET robust against interrupt injection

2026-08-06T17:21:31+00:00

commit 7e7f81cf6f5ca3311e526308f55d7c54d3ba71f9 upstream. An attacker injecting interrupts while the Safe-RET mitigation executes on machines affected by SRSO can neutralize the safe return sequence, potentially leading to data leakage through speculative execution. Fixup register state as if the Safe-RET sequence executed successfully by "emulating" it, in a manner of speaking, and avoid executing a RET instruction after returning from the interrupt. Co-developed-by: David Kaplan Signed-off-by: David Kaplan Signed-off-by: Borislav Petkov (AMD) Signed-off-by: Greg Kroah-Hartman

Linux 5.10.262

2026-07-30T10:56:00+00:00

Signed-off-by: Greg Kroah-Hartman

posix-cpu-timers: Prevent UAF caused by non-leader exec() race

2026-07-30T10:56:00+00:00

commit 920f893f735e92ba3a1cd9256899a186b161928d upstream. Wongi and Jungwoo decoded and reported a non-leader exec() related race which can result in an UAF: sys_timer_delete() exec() posix_cpu_timer_del() // Observes old leader p = pid_task(pid, pid_type); de_thread() switch_leader(); release_task(old_leader) __exit_signal(old_leader) sighand = lock(old_leader, sighand); posix_cpu_timers*_exit(); sighand = lock_task_sighand(p) unhash_task(old_leader); sh = lock(p, sighand) old_leader->sighand = NULL; unlock(sighand); (p->sighand == NULL) unlock(sh) return NULL; // Returns without action if(!sighand) return 0; free_posix_timer(); This is "harmless" unless the deleted timer was armed and enqueued in p->signal because on exec() a TGID targeted timer is inherited. As sys_timer_delete() freed the underlying posix timer object run_posix_cpu_timers() or any timerqueue related add/delete operations on other timers will access the freed object's timerqueue node, which results in an UAF. There is a similar problem vs. posix_cpu_timer_set(). For regular posix timers it just transiently returns -ESRCH to user space, but for the use case in do_cpu_nanosleep() it's the same UAF just that the k_itimer is allocated on the stack. Also posix_cpu_timer_rearm() fails to rearm the timer, which means it stops to expire. While debating solutions Frederic pointed out another problem: posix_cpu_timer_del(tmr) __exit_signal(p) posix_cpu_timers*_exit(p); unhash_task(p); p->sighand = NULL; sh = lock_task_sighand(p) sighand = p->sighand; if (!sighand) return NULL; lock(sighand); if (!sh) WARN_ON_ONCE(timer_queued(tmr)); On weakly ordered architectures it is not guaranteed that posix_cpu_timer_del() will observe the stores in posix_cpu_timers*_exit() when p->sighand is observed as NULL, which means the WARN() can be a false positive. Solve these issues by: 1) Changing the store in __exit_signal() to smp_store_release(). 2) Adding a smp_acquire__after_ctrl_dep() into the !sighand path of lock_task_sighand(). 3) Creating a helper function for looking up the task and locking sighand which does not return when sighand == NULL. Instead it retries the task lookup and only if that fails it gives up. 4) Using that helper in the three affected functions. #1/#2 ensures that the reader side which observes sighand == NULL also observes all preceeding stores, i.e. the stores in posix_cpu_timers*_exit() and the ones in unhash_task(). #3 ensures that the above described non-leader exec() situation is handled gracefully. When the task lookup returns the old leader, but sighand == NULL then it retries. In the non-leader exec() case the subsequent task lookup will observe the new leader due to #1/#2. In normal exit() scenarios the subsequent lookup fails. When the task lookup fails, the function also checks whether the timer is still enqueued and issues a warning if that's the case. Unfortunately there is nothing which can be done about it, but as the task is already not longer visible the timer should not be accessed anymore. This check also requires memory ordering, which is not provided when the first lookup fails. To achieve that the check is preceeded by a smp_rmb() which pairs with the smp_wmb() in write_seqlock() in __exit_signal(). That ensures that the stores in posix_cpu_timers*_exit() are visible. The history of the non-leader exec() issue goes back to the early days of posix CPU timers, which stored a pointer to the group leader task in the timer. That obviously fails when a non-leader exec() switches the leader. commit e0a70217107e ("posix-cpu-timers: workaround to suppress the problems with mt exec") added a temporary workaround for that in 2010 which survived about 10 years. The fix for the workaround changed the task pointer to a pid pointer, but failed to see the subtle race described above. So the Fixes tag picks that commit, which seems to be halfways accurate. Thanks to Frederic Weissbecker, Oleg Nesterov and Peter Zijlstra for review, feedback and suggestions and to Wongi and Jungwoo for the excellent bug report and analysis! Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Reported-by: Wongi Lee Reported-by: Jungwoo Lee Signed-off-by: Thomas Gleixner Reviewed-by: Oleg Nesterov Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin

Linux 5.10.261

2026-07-24T13:49:24+00:00

Link: https://lore.kernel.org/r/20260721152355.667394603@linuxfoundation.org Tested-by: Woody Suwalski Tested-by: Brett A C Sheffield Tested-by: Dominique Martinet Link: https://lore.kernel.org/r/20260722142749.280611149@linuxfoundation.org Tested-by: Brett A C Sheffield Tested-by: Florian Fainelli Tested-by: Pavel Machek (CIP) Tested-by: Mark Brown Tested-by: Barry K. Nathan Signed-off-by: Greg Kroah-Hartman

tools/resolve_btfids: Emit warnings and patch zero id for missing symbols

2026-07-24T13:49:24+00:00

commit 5aad03685185b5133a28e1ee1d4e98d3fd3642a3 upstream. Kernel functions referenced by .BTF_ids may be changed from global to static and get inlined or get renamed/removed, and thus disappears from BTF. This causes kernel build failure when resolve_btfids do id patch for symbols in .BTF_ids in vmlinux. Update resolve_btfids to emit warning messages and patch zero id for missing symbols instead of aborting kernel build process. Suggested-by: Andrii Nakryiko Signed-off-by: Hengqi Chen Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20210727132532.2473636-2-hengqi.chen@gmail.com Cc: "Barry K. Nathan" Signed-off-by: Greg Kroah-Hartman

tools/resolve_btfids: Fix some error messages

2026-07-24T13:49:24+00:00

commit 22e8ebe35a2e30ee19e02c41cacc99c2f896bc4b upstream. Add missing newlines and fix polarity of strerror argument. Signed-off-by: Brendan Jackman Signed-off-by: Alexei Starovoitov Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20201203102234.648540-1-jackmanb@google.com Cc: "Barry K. Nathan" Signed-off-by: Greg Kroah-Hartman

perf/x86/amd/core: Always use the NMI latency mitigation

2026-07-24T13:49:24+00:00

commit 73a4c02f94a98d94480c3e5c81450215a4da05ba upstream. Commit df4d29732fda ("perf/x86/amd: Change/fix NMI latency mitigation to use a timestamp") fixed handling of late-arriving NMIs but limited the mitigation to processors having X86_FEATURE_PERFCTR_CORE. However, it is unclear if processors without this feature are also affected. When Mediated vPMU is enabled on affected hardware, it is also possible to bypass the fix inside KVM guests if X86_FEATURE_PERFCTR_CORE is removed from the guest CPUID (e.g. using "-cpu host,-perfctr-core" with QEMU). Hence, use the mitigation at all times. Fixes: df4d29732fda ("perf/x86/amd: Change/fix NMI latency mitigation to use a timestamp") Signed-off-by: Sandipan Das Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/29a3c970da289ab8f24282933bdb36545c0403e8.1780325517.git.sandipan.das@amd.com Signed-off-by: Greg Kroah-Hartman

mld: fix suspicious RCU usage in __ipv6_dev_mc_dec()

2026-07-24T13:49:24+00:00

commit aa8caa767e319bad34a82bfce7da1ed2b9c0ed6f upstream. __ipv6_dev_mc_dec() internally uses sleepable functions so that caller must not acquire atomic locks. But caller, which is addrconf_verify_rtnl() acquires rcu_read_lock_bh(). So this warning occurs in the __ipv6_dev_mc_dec(). Test commands: ip netns add A ip link add veth0 type veth peer name veth1 ip link set veth1 netns A ip link set veth0 up ip netns exec A ip link set veth1 up ip a a 2001:db8::1/64 dev veth0 valid_lft 2 preferred_lft 1 Splat looks like: ============================ WARNING: suspicious RCU usage 5.12.0-rc6+ #515 Not tainted ----------------------------- kernel/sched/core.c:8294 Illegal context switch in RCU-bh read-side critical section! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 4 locks held by kworker/4:0/1997: #0: ffff88810bd72d48 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x761/0x1440 #1: ffff888105c8fe00 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x795/0x1440 #2: ffffffffb9279fb0 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 #3: ffffffffb8e30860 (rcu_read_lock_bh){....}-{1:2}, at: addrconf_verify_rtnl+0x23/0xc60 stack backtrace: CPU: 4 PID: 1997 Comm: kworker/4:0 Not tainted 5.12.0-rc6+ #515 Workqueue: ipv6_addrconf addrconf_verify_work Call Trace: dump_stack+0xa4/0xe5 ___might_sleep+0x27d/0x2b0 __mutex_lock+0xc8/0x13f0 ? lock_downgrade+0x690/0x690 ? __ipv6_dev_mc_dec+0x49/0x2a0 ? mark_held_locks+0xb7/0x120 ? mutex_lock_io_nested+0x1270/0x1270 ? lockdep_hardirqs_on_prepare+0x12c/0x3e0 ? _raw_spin_unlock_irqrestore+0x47/0x50 ? trace_hardirqs_on+0x41/0x120 ? __wake_up_common_lock+0xc9/0x100 ? __wake_up_common+0x620/0x620 ? memset+0x1f/0x40 ? netlink_broadcast_filtered+0x2c4/0xa70 ? __ipv6_dev_mc_dec+0x49/0x2a0 __ipv6_dev_mc_dec+0x49/0x2a0 ? netlink_broadcast_filtered+0x2f6/0xa70 addrconf_leave_solict.part.64+0xad/0xf0 ? addrconf_join_solict.part.63+0xf0/0xf0 ? nlmsg_notify+0x63/0x1b0 __ipv6_ifa_notify+0x22c/0x9c0 ? inet6_fill_ifaddr+0xbe0/0xbe0 ? lockdep_hardirqs_on_prepare+0x12c/0x3e0 ? __local_bh_enable_ip+0xa5/0xf0 ? ipv6_del_addr+0x347/0x870 ipv6_del_addr+0x3b1/0x870 ? addrconf_ifdown+0xfe0/0xfe0 ? rcu_read_lock_any_held.part.27+0x20/0x20 addrconf_verify_rtnl+0x8a9/0xc60 addrconf_verify_work+0xf/0x20 process_one_work+0x84c/0x1440 In order to avoid this problem, it uses rcu_read_unlock_bh() for a short time. RCU is used for avoiding freeing ifp(struct *inet6_ifaddr) while ifp is being used. But this will not be released even if rcu_read_unlock_bh() is used. Because before rcu_read_unlock_bh(), it uses in6_ifa_hold(ifp). So this is safe. Fixes: 63ed8de4be81 ("mld: add mc_lock for protecting per-interface mld data") Suggested-by: Eric Dumazet Reported-by: Eric Dumazet Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

ipv6: mcast: remove one synchronize_net() barrier in ipv6_mc_down()

2026-07-24T13:49:24+00:00

commit 17ef8efc00b34918b966388b2af0993811895a8c upstream. As discussed in the past (commit 2d3916f31891 ("ipv6: fix skb drops in igmp6_event_query() and igmp6_event_report()")) I think the synchronize_net() call in ipv6_mc_down() is not needed. Under load, synchronize_net() can last between 200 usec and 5 ms. KASAN seems to agree as well. Fixes: f185de28d9ae ("mld: add new workqueues for process mld events") Signed-off-by: Eric Dumazet Cc: Taehee Yoo Cc: Cong Wang Cc: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman