user/sven/linux.git/kernel, branch v5.16.1

bpf: Fix out of bounds access from invalid *_or_null type verification

2022-01-16T08:11:11Z

[ no upstream commit given implicitly fixed through the larger refactoring in c25b2ae136039ffa820c26138ed4a5e5f3ab3841 ] While auditing some other code, I noticed missing checks inside the pointer arithmetic simulation, more specifically, adjust_ptr_min_max_vals(). Several *_OR_NULL types are not rejected whereas they are _required_ to be rejected given the expectation is that they get promoted into a 'real' pointer type for the success case, that is, after an explicit != NULL check. One case which stands out and is accessible from unprivileged (iff enabled given disabled by default) is BPF ring buffer. From crafting a PoC, the NULL check can be bypassed through an offset, and its id marking will then lead to promotion of mem_or_null to a mem type. bpf_ringbuf_reserve() helper can trigger this case through passing of reserved flags, for example. func#0 @0 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 0: (7a) *(u64 *)(r10 -8) = 0 1: R1=ctx(id=0,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm 1: (18) r1 = 0x0 3: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm 3: (b7) r2 = 8 4: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R10=fp0 fp-8_w=mmmmmmmm 4: (b7) r3 = 0 5: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R3_w=invP0 R10=fp0 fp-8_w=mmmmmmmm 5: (85) call bpf_ringbuf_reserve#131 6: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 6: (bf) r6 = r0 7: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 7: (07) r0 += 1 8: R0_w=mem_or_null(id=2,ref_obj_id=2,off=1,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 8: (15) if r0 == 0x0 goto pc+4 R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 9: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 9: (62) *(u32 *)(r6 +0) = 0 R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 10: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 10: (bf) r1 = r6 11: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 11: (b7) r2 = 0 12: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R2_w=invP0 R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 12: (85) call bpf_ringbuf_submit#132 13: R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm 13: (b7) r0 = 0 14: R0_w=invP0 R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm 14: (95) exit from 8 to 13: safe processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0 OK All three commits, that is b121b341e598 ("bpf: Add PTR_TO_BTF_ID_OR_NULL support"), 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it"), and the afbf21dce668 ("bpf: Support readonly/readwrite buffers in verifier") suffer the same cause and their *_OR_NULL type pendants must be rejected in adjust_ptr_min_max_vals(). Make the test more robust by reusing reg_type_may_be_null() helper such that we catch all *_OR_NULL types we have today and in future. Note that pointer arithmetic on PTR_TO_BTF_ID, PTR_TO_RDONLY_BUF, and PTR_TO_RDWR_BUF is generally allowed. Fixes: b121b341e598 ("bpf: Add PTR_TO_BTF_ID_OR_NULL support") Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Fixes: afbf21dce668 ("bpf: Support readonly/readwrite buffers in verifier") Signed-off-by: Daniel Borkmann Signed-off-by: Greg Kroah-Hartman

workqueue: Fix unbind_workers() VS wq_worker_sleeping() race

2022-01-16T08:11:11Z

commit 45c753f5f24d2d4717acb38ce35e604ff9abcb50 upstream. At CPU-hotplug time, unbind_workers() may preempt a worker while it is going to sleep. In that case the following scenario can happen: unbind_workers() wq_worker_sleeping() -------------- ------------------- if (worker->flags & WORKER_NOT_RUNNING) return; //PREEMPTED by unbind_workers worker->flags |= WORKER_UNBOUND; [...] atomic_set(&pool->nr_running, 0); //resume to worker atomic_dec_and_test(&pool->nr_running); After unbind_worker() resets pool->nr_running, the value is expected to remain 0 until the pool ever gets rebound in case cpu_up() is called on the target CPU in the future. But here the race leaves pool->nr_running with a value of -1, triggering the following warning when the worker goes idle: WARNING: CPU: 3 PID: 34 at kernel/workqueue.c:1823 worker_enter_idle+0x95/0xc0 Modules linked in: CPU: 3 PID: 34 Comm: kworker/3:0 Not tainted 5.16.0-rc1+ #34 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014 Workqueue: 0x0 (rcu_par_gp) RIP: 0010:worker_enter_idle+0x95/0xc0 Code: 04 85 f8 ff ff ff 39 c1 7f 09 48 8b 43 50 48 85 c0 74 1b 83 e2 04 75 99 8b 43 34 39 43 30 75 91 8b 83 00 03 00 00 85 c0 74 87 <0f> 0b 5b c3 48 8b 35 70 f1 37 01 48 8d 7b 48 48 81 c6 e0 93 0 RSP: 0000:ffff9b7680277ed0 EFLAGS: 00010086 RAX: 00000000ffffffff RBX: ffff93465eae9c00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9346418a0000 RDI: ffff934641057140 RBP: ffff934641057170 R08: 0000000000000001 R09: ffff9346418a0080 R10: ffff9b768027fdf0 R11: 0000000000002400 R12: ffff93465eae9c20 R13: ffff93465eae9c20 R14: ffff93465eae9c70 R15: ffff934641057140 FS: 0000000000000000(0000) GS:ffff93465eac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000001cc0c000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: worker_thread+0x89/0x3d0 ? process_one_work+0x400/0x400 kthread+0x162/0x190 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x22/0x30 Also due to this incorrect "nr_running == -1", all sorts of hazards can happen, starting with queued works being ignored because no workers are awaken at insert_work() time. Fix this with checking again the worker flags while pool->lock is locked. Fixes: b945efcdd07d ("sched: Remove pointless preemption disable in sched_submit_work()") Reviewed-by: Lai Jiangshan Tested-by: Paul E. McKenney Acked-by: Peter Zijlstra (Intel) Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Paul E. McKenney Cc: Sebastian Andrzej Siewior Cc: Daniel Bristot de Oliveira Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

workqueue: Fix unbind_workers() VS wq_worker_running() race

2022-01-16T08:11:11Z

commit 07edfece8bcb0580a1828d939e6f8d91a8603eb2 upstream. At CPU-hotplug time, unbind_worker() may preempt a worker while it is waking up. In that case the following scenario can happen: unbind_workers() wq_worker_running() -------------- ------------------- if (!(worker->flags & WORKER_NOT_RUNNING)) //PREEMPTED by unbind_workers worker->flags |= WORKER_UNBOUND; [...] atomic_set(&pool->nr_running, 0); //resume to worker atomic_inc(&worker->pool->nr_running); After unbind_worker() resets pool->nr_running, the value is expected to remain 0 until the pool ever gets rebound in case cpu_up() is called on the target CPU in the future. But here the race leaves pool->nr_running with a value of 1, triggering the following warning when the worker goes idle: WARNING: CPU: 3 PID: 34 at kernel/workqueue.c:1823 worker_enter_idle+0x95/0xc0 Modules linked in: CPU: 3 PID: 34 Comm: kworker/3:0 Not tainted 5.16.0-rc1+ #34 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014 Workqueue: 0x0 (rcu_par_gp) RIP: 0010:worker_enter_idle+0x95/0xc0 Code: 04 85 f8 ff ff ff 39 c1 7f 09 48 8b 43 50 48 85 c0 74 1b 83 e2 04 75 99 8b 43 34 39 43 30 75 91 8b 83 00 03 00 00 85 c0 74 87 <0f> 0b 5b c3 48 8b 35 70 f1 37 01 48 8d 7b 48 48 81 c6 e0 93 0 RSP: 0000:ffff9b7680277ed0 EFLAGS: 00010086 RAX: 00000000ffffffff RBX: ffff93465eae9c00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9346418a0000 RDI: ffff934641057140 RBP: ffff934641057170 R08: 0000000000000001 R09: ffff9346418a0080 R10: ffff9b768027fdf0 R11: 0000000000002400 R12: ffff93465eae9c20 R13: ffff93465eae9c20 R14: ffff93465eae9c70 R15: ffff934641057140 FS: 0000000000000000(0000) GS:ffff93465eac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000001cc0c000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: worker_thread+0x89/0x3d0 ? process_one_work+0x400/0x400 kthread+0x162/0x190 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x22/0x30 Also due to this incorrect "nr_running == 1", further queued work may end up not being served, because no worker is awaken at work insert time. This raises rcutorture writer stalls for example. Fix this with disabling preemption in the right place in wq_worker_running(). It's worth noting that if the worker migrates and runs concurrently with unbind_workers(), it is guaranteed to see the WORKER_UNBOUND flag update due to set_cpus_allowed_ptr() acquiring/releasing rq->lock. Fixes: 6d25be5782e4 ("sched/core, workqueues: Distangle worker accounting from rq lock") Reviewed-by: Lai Jiangshan Tested-by: Paul E. McKenney Acked-by: Peter Zijlstra (Intel) Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Sebastian Andrzej Siewior Cc: Daniel Bristot de Oliveira Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-5.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2022-01-07T23:58:06Z

Pull cgroup fixes from Tejun Heo: "This contains the cgroup.procs permission check fixes so that they use the credentials at the time of open rather than write, which also fixes the cgroup namespace lifetime bug" * 'for-5.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: selftests: cgroup: Test open-time cgroup namespace usage for migration checks selftests: cgroup: Test open-time credential usage for migration checks selftests: cgroup: Make cg_create() use 0755 for permission instead of 0644 cgroup: Use open-time cgroup namespace for process migration perm checks cgroup: Allocate cgroup_file_ctx for kernfs_open_file->priv cgroup: Use open-time credentials for process migraton perm checks

Merge tag 'trace-v5.16-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2022-01-06T23:00:43Z

Pull tracing fixes from Steven Rostedt: "Three minor tracing fixes: - Fix missing prototypes in sample module for direct functions - Fix check of valid buffer in get_trace_buf() - Fix annotations of percpu pointers" * tag 'trace-v5.16-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Tag trace_percpu_buffer as a percpu pointer tracing: Fix check for trace_percpu_buffer validity in get_trace_buf() ftrace/samples: Add missing prototypes direct functions

cgroup: Use open-time cgroup namespace for process migration perm checks

2022-01-06T21:02:29Z

cgroup process migration permission checks are performed at write time as whether a given operation is allowed or not is dependent on the content of the write - the PID. This currently uses current's cgroup namespace which is a potential security weakness as it may allow scenarios where a less privileged process tricks a more privileged one into writing into a fd that it created. This patch makes cgroup remember the cgroup namespace at the time of open and uses it for migration permission checks instad of current's. Note that this only applies to cgroup2 as cgroup1 doesn't have namespace support. This also fixes a use-after-free bug on cgroupns reported in https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com Note that backporting this fix also requires the preceding patch. Reported-by: "Eric W. Biederman" Suggested-by: Linus Torvalds Cc: Michal Koutný Cc: Oleg Nesterov Reviewed-by: Michal Koutný Reported-by: syzbot+50f5cf33a284ce738b62@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/00000000000048c15c05d0083397@google.com Fixes: 5136f6365ce3 ("cgroup: implement "nsdelegate" mount option") Signed-off-by: Tejun Heo

cgroup: Allocate cgroup_file_ctx for kernfs_open_file->priv

2022-01-06T21:02:29Z

of->priv is currently used by each interface file implementation to store private information. This patch collects the current two private data usages into struct cgroup_file_ctx which is allocated and freed by the common path. This allows generic private data which applies to multiple files, which will be used to in the following patch. Note that cgroup_procs iterator is now embedded as procs.iter in the new cgroup_file_ctx so that it doesn't need to be allocated and freed separately. v2: union dropped from cgroup_file_ctx and the procs iterator is embedded in cgroup_file_ctx as suggested by Linus. v3: Michal pointed out that cgroup1's procs pidlist uses of->priv too. Converted. Didn't change to embedded allocation as cgroup1 pidlists get stored for caching. Signed-off-by: Tejun Heo Cc: Linus Torvalds Reviewed-by: Michal Koutný

cgroup: Use open-time credentials for process migraton perm checks

2022-01-06T21:02:28Z

tracing: Tag trace_percpu_buffer as a percpu pointer

2022-01-05T23:53:49Z

Tag trace_percpu_buffer as a percpu pointer to resolve warnings reported by sparse: /linux/kernel/trace/trace.c:3218:46: warning: incorrect type in initializer (different address spaces) /linux/kernel/trace/trace.c:3218:46: expected void const [noderef] __percpu *__vpp_verify /linux/kernel/trace/trace.c:3218:46: got struct trace_buffer_struct * /linux/kernel/trace/trace.c:3234:9: warning: incorrect type in initializer (different address spaces) /linux/kernel/trace/trace.c:3234:9: expected void const [noderef] __percpu *__vpp_verify /linux/kernel/trace/trace.c:3234:9: got int * Link: https://lkml.kernel.org/r/ebabd3f23101d89cb75671b68b6f819f5edc830b.1640255304.git.naveen.n.rao@linux.vnet.ibm.com Cc: stable@vger.kernel.org Reported-by: kernel test robot Fixes: 07d777fe8c398 ("tracing: Add percpu buffers for trace_printk()") Signed-off-by: Naveen N. Rao Signed-off-by: Steven Rostedt

tracing: Fix check for trace_percpu_buffer validity in get_trace_buf()

2022-01-05T23:51:25Z

With the new osnoise tracer, we are seeing the below splat: Kernel attempted to read user page (c7d880000) - exploit attempt? (uid: 0) BUG: Unable to handle kernel data access on read at 0xc7d880000 Faulting instruction address: 0xc0000000002ffa10 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries ... NIP [c0000000002ffa10] __trace_array_vprintk.part.0+0x70/0x2f0 LR [c0000000002ff9fc] __trace_array_vprintk.part.0+0x5c/0x2f0 Call Trace: [c0000008bdd73b80] [c0000000001c49cc] put_prev_task_fair+0x3c/0x60 (unreliable) [c0000008bdd73be0] [c000000000301430] trace_array_printk_buf+0x70/0x90 [c0000008bdd73c00] [c0000000003178b0] trace_sched_switch_callback+0x250/0x290 [c0000008bdd73c90] [c000000000e70d60] __schedule+0x410/0x710 [c0000008bdd73d40] [c000000000e710c0] schedule+0x60/0x130 [c0000008bdd73d70] [c000000000030614] interrupt_exit_user_prepare_main+0x264/0x270 [c0000008bdd73de0] [c000000000030a70] syscall_exit_prepare+0x150/0x180 [c0000008bdd73e10] [c00000000000c174] system_call_vectored_common+0xf4/0x278 osnoise tracer on ppc64le is triggering osnoise_taint() for negative duration in get_int_safe_duration() called from trace_sched_switch_callback()->thread_exit(). The problem though is that the check for a valid trace_percpu_buffer is incorrect in get_trace_buf(). The check is being done after calculating the pointer for the current cpu, rather than on the main percpu pointer. Fix the check to be against trace_percpu_buffer. Link: https://lkml.kernel.org/r/a920e4272e0b0635cf20c444707cbce1b2c8973d.1640255304.git.naveen.n.rao@linux.vnet.ibm.com Cc: stable@vger.kernel.org Fixes: e2ace001176dc9 ("tracing: Choose static tp_printk buffer by explicit nesting count") Signed-off-by: Naveen N. Rao Signed-off-by: Steven Rostedt