linux-dev/kernel/bpf, branch master

bpf: Fix wrong reg type conversion in release_reference()

2022-11-03T23:24:12Z

Some helper functions will allocate memory. To avoid memory leaks, the verifier requires the eBPF program to release these memories by calling the corresponding helper functions. When a resource is released, all pointer registers corresponding to the resource should be invalidated. The verifier use release_references() to do this job, by apply __mark_reg_unknown() to each relevant register. It will give these registers the type of SCALAR_VALUE. A register that will contain a pointer value at runtime, but of type SCALAR_VALUE, which may allow the unprivileged user to get a kernel pointer by storing this register into a map. Using __mark_reg_not_init() while NOT allow_ptr_leaks can mitigate this problem. Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier") Signed-off-by: Youlin Li Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20221103093440.3161-1-liulin063@gmail.com

bpf, verifier: Fix memory leak in array reallocation for stack state

2022-11-01T13:29:16Z

If an error (NULL) is returned by krealloc(), callers of realloc_array() were setting their allocation pointers to NULL, but on error krealloc() does not touch the original allocation. This would result in a memory resource leak. Instead, free the old allocation on the error handling path. The memory leak information is as follows as also reported by Zhengchao: unreferenced object 0xffff888019801800 (size 256): comm "bpf_repo", pid 6490, jiffies 4294959200 (age 17.170s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000b211474b>] __kmalloc_node_track_caller+0x45/0xc0 [<0000000086712a0b>] krealloc+0x83/0xd0 [<00000000139aab02>] realloc_array+0x82/0xe2 [<00000000b1ca41d1>] grow_stack_state+0xfb/0x186 [<00000000cd6f36d2>] check_mem_access.cold+0x141/0x1341 [<0000000081780455>] do_check_common+0x5358/0xb350 [<0000000015f6b091>] bpf_check.cold+0xc3/0x29d [<000000002973c690>] bpf_prog_load+0x13db/0x2240 [<00000000028d1644>] __sys_bpf+0x1605/0x4ce0 [<00000000053f29bd>] __x64_sys_bpf+0x75/0xb0 [<0000000056fedaf5>] do_syscall_64+0x35/0x80 [<000000002bd58261>] entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: c69431aab67a ("bpf: verifier: Improve function state reallocation") Reported-by: Zhengchao Shao Reported-by: Kees Cook Signed-off-by: Kees Cook Signed-off-by: Daniel Borkmann Reviewed-by: Bill Wendling Cc: Lorenz Bauer Link: https://lore.kernel.org/bpf/20221029025433.2533810-1-keescook@chromium.org

Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2022-10-24T17:32:01Z

Alexei Starovoitov says: ==================== pull-request: bpf 2022-10-23 We've added 7 non-merge commits during the last 18 day(s) which contain a total of 8 files changed, 69 insertions(+), 5 deletions(-). The main changes are: 1) Wait for busy refill_work when destroying bpf memory allocator, from Hou. 2) Allow bpf_user_ringbuf_drain() callbacks to return 1, from David. 3) Fix dispatcher patchable function entry to 5 bytes nop, from Jiri. 4) Prevent decl_tag from being referenced in func_proto, from Stanislav. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: bpf: Use __llist_del_all() whenever possbile during memory draining bpf: Wait for busy refill_work when destroying bpf memory allocator bpf: Fix dispatcher patchable function entry to 5 bytes nop bpf: prevent decl_tag from being referenced in func_proto selftests/bpf: Add reproducer for decl_tag in func_proto return type selftests/bpf: Make bpf_user_ringbuf_drain() selftest callback return 1 bpf: Allow bpf_user_ringbuf_drain() callbacks to return 1 ==================== Link: https://lore.kernel.org/r/20221023192244.81137-1-alexei.starovoitov@gmail.com Signed-off-by: Jakub Kicinski

bpf: Use __llist_del_all() whenever possbile during memory draining

2022-10-22T02:17:38Z

Except for waiting_for_gp list, there are no concurrent operations on free_by_rcu, free_llist and free_llist_extra lists, so use __llist_del_all() instead of llist_del_all(). waiting_for_gp list can be deleted by RCU callback concurrently, so still use llist_del_all(). Acked-by: Stanislav Fomichev Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20221021114913.60508-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov

bpf: Wait for busy refill_work when destroying bpf memory allocator

2022-10-22T02:17:38Z

A busy irq work is an unfinished irq work and it can be either in the pending state or in the running state. When destroying bpf memory allocator, refill_work may be busy for PREEMPT_RT kernel in which irq work is invoked in a per-CPU RT-kthread. It is also possible for kernel with arch_irq_work_has_interrupt() being false (e.g. 1-cpu arm32 host or mips) and irq work is inovked in timer interrupt. The busy refill_work leads to various issues. The obvious one is that there will be concurrent operations on free_by_rcu and free_list between irq work and memory draining. Another one is call_rcu_in_progress will not be reliable for the checking of pending RCU callback because do_call_rcu() may have not been invoked by irq work yet. The other is there will be use-after-free if irq work is freed before the callback of irq work is invoked as shown below: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 12ab94067 P4D 12ab94067 PUD 1796b4067 PMD 0 Oops: 0010 [#1] PREEMPT_RT SMP CPU: 5 PID: 64 Comm: irq_work/5 Not tainted 6.0.0-rt11+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffffadc080293e78 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffffcdc07fb6a388 RCX: ffffa05000a2e000 RDX: ffffa05000a2e000 RSI: ffffffff96cc9827 RDI: ffffcdc07fb6a388 ...... Call Trace: irq_work_single+0x24/0x60 irq_work_run_list+0x24/0x30 run_irq_workd+0x23/0x30 smpboot_thread_fn+0x203/0x300 kthread+0x126/0x150 ret_from_fork+0x1f/0x30 Considering the ease of concurrency handling, no overhead for irq_work_sync() under non-PREEMPT_RT kernel and has-irq-work-interrupt kernel and the short wait time used for irq_work_sync() under PREEMPT_RT (When running two test_maps on PREEMPT_RT kernel and 72-cpus host, the max wait time is about 8ms and the 99th percentile is 10us), just using irq_work_sync() to wait for busy refill_work to complete before memory draining and memory freeing. Fixes: 7c8199e24fa0 ("bpf: Introduce any context BPF specific memory allocator.") Acked-by: Stanislav Fomichev Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20221021114913.60508-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov

bpf: Fix dispatcher patchable function entry to 5 bytes nop

2022-10-21T01:57:51Z

The patchable_function_entry(5) might output 5 single nop instructions (depends on toolchain), which will clash with bpf_arch_text_poke check for 5 bytes nop instruction. Adding early init call for dispatcher that checks and change the patchable entry into expected 5 nop instruction if needed. There's no need to take text_mutex, because we are using it in early init call which is called at pre-smp time. Fixes: ceea991a019c ("bpf: Move bpf_dispatcher function out of ftrace locations") Signed-off-by: Jiri Olsa Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20221018075934.574415-1-jolsa@kernel.org Signed-off-by: Alexei Starovoitov

Merge tag 'cgroup-for-6.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2022-10-18T01:52:43Z

Pull cgroup fixes from Tejun Heo: - Fix a recent regression where a sleeping kernfs function is called with css_set_lock (spinlock) held - Revert the commit to enable cgroup1 support for cgroup_get_from_fd/file() Multiple users assume that the lookup only works for cgroup2 and breaks when fed a cgroup1 file. Instead, introduce a separate set of functions to lookup both v1 and v2 and use them where the user explicitly wants to support both versions. - Compat update for tools/perf/util/bpf_skel/bperf_cgroup.bpf.c. - Add Josef Bacik as a blkcg maintainer. * tag 'cgroup-for-6.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: blkcg: Update MAINTAINERS entry mm: cgroup: fix comments for get from fd/file helpers perf stat: Support old kernels for bperf cgroup counting bpf: cgroup_iter: support cgroup1 using cgroup fd cgroup: add cgroup_v1v2_get_from_[fd/file]() Revert "cgroup: enable cgroup_get_from_file() on cgroup1" cgroup: Reorganize css_set_lock and kernfs path processing

bpf: prevent decl_tag from being referenced in func_proto

2022-10-17T17:56:12Z

Syzkaller was able to hit the following issue: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 3609 at kernel/bpf/btf.c:1946 btf_type_id_size+0x2d5/0x9d0 kernel/bpf/btf.c:1946 Modules linked in: CPU: 0 PID: 3609 Comm: syz-executor361 Not tainted 6.0.0-syzkaller-02734-g0326074ff465 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022 RIP: 0010:btf_type_id_size+0x2d5/0x9d0 kernel/bpf/btf.c:1946 Code: ef e8 7f 8e e4 ff 41 83 ff 0b 77 28 f6 44 24 10 18 75 3f e8 6d 91 e4 ff 44 89 fe bf 0e 00 00 00 e8 20 8e e4 ff e8 5b 91 e4 ff <0f> 0b 45 31 f6 e9 98 02 00 00 41 83 ff 12 74 18 e8 46 91 e4 ff 44 RSP: 0018:ffffc90003cefb40 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000 RDX: ffff8880259c0000 RSI: ffffffff81968415 RDI: 0000000000000005 RBP: ffff88801270ca00 R08: 0000000000000005 R09: 000000000000000e R10: 0000000000000011 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000011 R14: ffff888026ee6424 R15: 0000000000000011 FS: 000055555641b300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000f2e258 CR3: 000000007110e000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: btf_func_proto_check kernel/bpf/btf.c:4447 [inline] btf_check_all_types kernel/bpf/btf.c:4723 [inline] btf_parse_type_sec kernel/bpf/btf.c:4752 [inline] btf_parse kernel/bpf/btf.c:5026 [inline] btf_new_fd+0x1926/0x1e70 kernel/bpf/btf.c:6892 bpf_btf_load kernel/bpf/syscall.c:4324 [inline] __sys_bpf+0xb7d/0x4cf0 kernel/bpf/syscall.c:5010 __do_sys_bpf kernel/bpf/syscall.c:5069 [inline] __se_sys_bpf kernel/bpf/syscall.c:5067 [inline] __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:5067 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f0fbae41c69 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc8aeb6228 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0fbae41c69 RDX: 0000000000000020 RSI: 0000000020000140 RDI: 0000000000000012 RBP: 00007f0fbae05e10 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000ffffffff R11: 0000000000000246 R12: 00007f0fbae05ea0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Looks like it tries to create a func_proto which return type is decl_tag. For the details, see Martin's spot on analysis in [0]. 0: https://lore.kernel.org/bpf/CAKH8qBuQDLva_hHxxBuZzyAcYNO4ejhovz6TQeVSk8HY-2SO6g@mail.gmail.com/T/#mea6524b3fcd6298347432226e81b1e6155efc62c Cc: Yonghong Song Cc: Martin KaFai Lau Fixes: bd16dee66ae4 ("bpf: Add BTF_KIND_DECL_TAG typedef support") Reported-by: syzbot+d8bd751aef7c6b39a344@syzkaller.appspotmail.com Signed-off-by: Stanislav Fomichev Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20221015002444.2680969-2-sdf@google.com Signed-off-by: Martin KaFai Lau

bpf: Allow bpf_user_ringbuf_drain() callbacks to return 1

2022-10-13T15:27:37Z

The bpf_user_ringbuf_drain() helper function allows a BPF program to specify a callback that is invoked when draining entries from a BPF_MAP_TYPE_USER_RINGBUF ring buffer map. The API is meant to allow the callback to return 0 if it wants to continue draining samples, and 1 if it's done draining. Unfortunately, bpf_user_ringbuf_drain() landed shortly after commit 1bfe26fb0827 ("bpf: Add verifier support for custom callback return range"), which changed the default behavior of callbacks to only support returning 0. This patch corrects that oversight by allowing bpf_user_ringbuf_drain() callbacks to return 0 or 1. A follow-on patch will update the user_ringbuf selftests to also return 1 from a bpf_user_ringbuf_drain() callback to prevent this from regressing in the future. Fixes: 205715673844 ("bpf: Add bpf_user_ringbuf_drain() helper") Signed-off-by: David Vernet Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221012232015.1510043-2-void@manifault.com

treewide: use get_random_u32() when possible

2022-10-11T23:42:58Z

The prandom_u32() function has been a deprecated inline wrapper around get_random_u32() for several releases now, and compiles down to the exact same code. Replace the deprecated wrapper with a direct call to the real function. The same also applies to get_random_int(), which is just a wrapper around get_random_u32(). This was done as a basic find and replace. Reviewed-by: Greg Kroah-Hartman Reviewed-by: Kees Cook Reviewed-by: Yury Norov Reviewed-by: Jan Kara # for ext4 Acked-by: Toke Høiland-Jørgensen # for sch_cake Acked-by: Chuck Lever # for nfsd Acked-by: Jakub Kicinski Acked-by: Mika Westerberg # for thunderbolt Acked-by: Darrick J. Wong # for xfs Acked-by: Helge Deller # for parisc Acked-by: Heiko Carstens # for s390 Signed-off-by: Jason A. Donenfeld