> On 17 Dec 2022, at 1:07 PM, Yonghong Song <yhs@xxxxxxxx> wrote: > > > > On 12/14/22 11:49 PM, Hao Sun wrote: >> Hi, >> The following KASAN report can be triggered by loading and test >> running this simple BPF prog with a random data/ctx: >> 0: r0 = bpf_get_current_task_btf ; >> R0_w=trusted_ptr_task_struct(off=0,imm=0) >> 1: r0 = *(u32 *)(r0 +8192) ; >> R0_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) >> 2: exit >> I've simplified the C reproducer but didn't find the root cause. >> JIT was disabled, and the interpreter triggered UAF when executing >> the load insn. A slab-out-of-bound read can also be triggered: >> https://pastebin.com/raw/g9zXr8jU >> This can be reproduced on: >> HEAD commit: b148c8b9b926 selftests/bpf: Add few corner cases to test >> padding handling of btf_dump >> git tree: bpf-next >> console log: https://pastebin.com/raw/1EUi9tJe >> kernel config: https://pastebin.com/raw/rgY3AJDZ >> C reproducer: https://pastebin.com/raw/cfVGuCBm > > I I tried with your above kernel config and C reproducer and cannot reproduce the kasan issue you reported. > > [root@arch-fb-vm1 bpf-next]# ./a.out > func#0 @0 > 0: R1=ctx(off=0,imm=0) R10=fp0 > 0: (85) call bpf_get_current_task_btf#158 ; R0_w=trusted_ptr_task_struct(off=0,imm=0) > 1: (61) r0 = *(u32 *)(r0 +8192) ; R0_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) > 2: (95) exit > processed 3 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 > > prog fd: 3 > [root@arch-fb-vm1 bpf-next]# > > Your config indeed has kasan on. Hi, I can still reproduce this on a latest bpf-next build: 0e43662e61f25 (“tools/resolve_btfids: Use pkg-config to locate libelf”). The simplified C reproducer sometime need to be run twice to trigger the UAF. Also note that interpreter is required. Here is the original C reproducer that loads and runs the BPF prog continuously for your convenience: https://pastebin.com/raw/WSJuNnVU > >> ================================================================== >> BUG: KASAN: use-after-free in ___bpf_prog_run+0x7f35/0x8fd0 >> kernel/bpf/core.c:1937 >> Read of size 4 at addr ffff88801f1f2000 by task a.out/7137 >> CPU: 3 PID: 7137 Comm: a.out Not tainted >> 6.1.0-rc8-02212-gef3911a3e4d6-dirty #137 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux >> 1.16.1-1-1 04/01/2014 >> Call Trace: >> <TASK> >> __dump_stack lib/dump_stack.c:88 [inline] >> dump_stack_lvl+0x100/0x178 lib/dump_stack.c:106 >> print_address_description mm/kasan/report.c:284 [inline] >> print_report+0x167/0x46c mm/kasan/report.c:395 >> kasan_report+0xbf/0x1e0 mm/kasan/report.c:495 >> ___bpf_prog_run+0x7f35/0x8fd0 kernel/bpf/core.c:1937 >> __bpf_prog_run32+0x9d/0xe0 kernel/bpf/core.c:2045 >> bpf_dispatcher_nop_func include/linux/bpf.h:1082 [inline] >> __bpf_prog_run include/linux/filter.h:600 [inline] >> bpf_prog_run include/linux/filter.h:607 [inline] >> bpf_test_run+0x38e/0x980 net/bpf/test_run.c:402 >> bpf_prog_test_run_skb+0xb67/0x1dc0 net/bpf/test_run.c:1187 >> bpf_prog_test_run kernel/bpf/syscall.c:3644 [inline] >> __sys_bpf+0x1293/0x5840 kernel/bpf/syscall.c:4997 >> __do_sys_bpf kernel/bpf/syscall.c:5083 [inline] >> __se_sys_bpf kernel/bpf/syscall.c:5081 [inline] >> __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5081 >> do_syscall_x64 arch/x86/entry/common.c:50 [inline] >> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 >> entry_SYSCALL_64_after_hwframe+0x63/0xcd >> RIP: 0033:0x7fb8adae4469 >> Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 8b 0d ff 49 2b 00 f7 d8 64 89 01 48 >> RSP: 002b:00007fff514ad148 EFLAGS: 00000203 ORIG_RAX: 0000000000000141 >> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb8adae4469 >> RDX: 0000000000000025 RSI: 0000000020000200 RDI: 000000000000000a >> RBP: 00007fff514ae2f0 R08: 00007fb8adb2dd70 R09: 00000b4100000218 >> R10: e67c061720b91d86 R11: 0000000000000203 R12: 000055ed87c00760 >> R13: 00007fff514ae3d0 R14: 0000000000000000 R15: 0000000000000000 >> </TASK> >> Allocated by task 7128: >> kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 >> kasan_set_track+0x25/0x30 mm/kasan/common.c:52 >> __kasan_slab_alloc+0x84/0x90 mm/kasan/common.c:325 >> kasan_slab_alloc include/linux/kasan.h:201 [inline] >> slab_post_alloc_hook mm/slab.h:737 [inline] >> slab_alloc_node mm/slub.c:3398 [inline] >> kmem_cache_alloc_node+0x166/0x410 mm/slub.c:3443 >> alloc_task_struct_node kernel/fork.c:171 [inline] >> dup_task_struct kernel/fork.c:966 [inline] >> copy_process+0x5db/0x6f40 kernel/fork.c:2084 >> kernel_clone+0xe8/0x980 kernel/fork.c:2671 >> __do_sys_clone+0xc0/0x100 kernel/fork.c:2812 >> do_syscall_x64 arch/x86/entry/common.c:50 [inline] >> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 >> entry_SYSCALL_64_after_hwframe+0x63/0xcd >> Freed by task 0: >> kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 >> kasan_set_track+0x25/0x30 mm/kasan/common.c:52 >> kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:511 >> ____kasan_slab_free mm/kasan/common.c:236 [inline] >> ____kasan_slab_free+0x15e/0x1b0 mm/kasan/common.c:200 >> kasan_slab_free include/linux/kasan.h:177 [inline] >> slab_free_hook mm/slub.c:1724 [inline] >> slab_free_freelist_hook+0x10b/0x1e0 mm/slub.c:1750 >> slab_free mm/slub.c:3661 [inline] >> kmem_cache_free+0xee/0x5b0 mm/slub.c:3683 >> put_task_struct include/linux/sched/task.h:119 [inline] >> delayed_put_task_struct+0x274/0x3e0 kernel/exit.c:178 >> rcu_do_batch kernel/rcu/tree.c:2250 [inline] >> rcu_core+0x835/0x1980 kernel/rcu/tree.c:2510 >> __do_softirq+0x1f7/0xaf6 kernel/softirq.c:571 >> Last potentially related work creation: >> kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 >> __kasan_record_aux_stack+0xbf/0xd0 mm/kasan/generic.c:481 >> call_rcu+0x9e/0x790 kernel/rcu/tree.c:2798 >> put_task_struct_rcu_user kernel/exit.c:184 [inline] >> put_task_struct_rcu_user+0x83/0xc0 kernel/exit.c:181 >> release_task+0xe9e/0x1ae0 kernel/exit.c:234 >> wait_task_zombie kernel/exit.c:1136 [inline] >> wait_consider_task+0x17d8/0x3e70 kernel/exit.c:1363 >> do_wait_thread kernel/exit.c:1426 [inline] >> do_wait+0x75f/0xdc0 kernel/exit.c:1543 >> kernel_wait4+0x153/0x260 kernel/exit.c:1706 >> __do_sys_wait4+0x147/0x160 kernel/exit.c:1734 >> do_syscall_x64 arch/x86/entry/common.c:50 [inline] >> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 >> entry_SYSCALL_64_after_hwframe+0x63/0xcd >> Second to last potentially related work creation: >> kasan_save_stack+0x20/0x40 mm/kasan/common.c:45 >> __kasan_record_aux_stack+0xbf/0xd0 mm/kasan/generic.c:481 >> call_rcu+0x9e/0x790 kernel/rcu/tree.c:2798 >> put_task_struct_rcu_user kernel/exit.c:184 [inline] >> put_task_struct_rcu_user+0x83/0xc0 kernel/exit.c:181 >> release_task+0xe9e/0x1ae0 kernel/exit.c:234 >> wait_task_zombie kernel/exit.c:1136 [inline] >> wait_consider_task+0x17d8/0x3e70 kernel/exit.c:1363 >> do_wait_thread kernel/exit.c:1426 [inline] >> do_wait+0x75f/0xdc0 kernel/exit.c:1543 >> kernel_wait4+0x153/0x260 kernel/exit.c:1706 >> __do_sys_wait4+0x147/0x160 kernel/exit.c:1734 >> do_syscall_x64 arch/x86/entry/common.c:50 [inline] >> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 >> entry_SYSCALL_64_after_hwframe+0x63/0xcd >> The buggy address belongs to the object at ffff88801f1f1d80 >> which belongs to the cache task_struct of size 7240 >> The buggy address is located 640 bytes inside of >> 7240-byte region [ffff88801f1f1d80, ffff88801f1f39c8) >> The buggy address belongs to the physical page: >> page:ffffea00007c7c00 refcount:1 mapcount:0 mapping:0000000000000000 >> index:0x0 pfn:0x1f1f0 >> head:ffffea00007c7c00 order:3 compound_mapcount:0 compound_pincount:0 >> memcg:ffff888013b2c081 >> flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) >> raw: 00fff00000010200 ffffea00005e4200 dead000000000002 ffff88801322a000 >> raw: 0000000000000000 0000000080040004 00000001ffffffff ffff888013b2c081 >> page dumped because: kasan: bad access detected >> page_owner tracks the page as allocated >> page last allocated via order 3, migratetype Unmovable, gfp_mask >> 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), >> pid 16, tgid 16 (kworker/u17:1), ts 3731671201, free_ts 0 >> prep_new_page mm/page_alloc.c:2539 [inline] >> get_page_from_freelist+0x10ce/0x2db0 mm/page_alloc.c:4291 >> __alloc_pages+0x1c8/0x5c0 mm/page_alloc.c:5558 >> alloc_pages+0x1a9/0x270 mm/mempolicy.c:2285 >> alloc_slab_page mm/slub.c:1794 [inline] >> allocate_slab+0x24e/0x340 mm/slub.c:1939 >> new_slab mm/slub.c:1992 [inline] >> ___slab_alloc+0x89a/0x1400 mm/slub.c:3180 >> __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279 >> slab_alloc_node mm/slub.c:3364 [inline] >> kmem_cache_alloc_node+0x12e/0x410 mm/slub.c:3443 >> alloc_task_struct_node kernel/fork.c:171 [inline] >> dup_task_struct kernel/fork.c:966 [inline] >> copy_process+0x5db/0x6f40 kernel/fork.c:2084 >> kernel_clone+0xe8/0x980 kernel/fork.c:2671 >> user_mode_thread+0xb4/0xf0 kernel/fork.c:2747 >> call_usermodehelper_exec_work kernel/umh.c:175 [inline] >> call_usermodehelper_exec_work+0xcb/0x170 kernel/umh.c:161 >> process_one_work+0xa33/0x1720 kernel/workqueue.c:2289 >> worker_thread+0x67d/0x10e0 kernel/workqueue.c:2436 >> kthread+0x2e4/0x3a0 kernel/kthread.c:376 >> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 >> page_owner free stack trace missing >> Memory state around the buggy address: >> ffff88801f1f1f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff88801f1f1f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff88801f1f2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ^ >> ffff88801f1f2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff88801f1f2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ==================================================================
