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syzkaller-bugs@googlegroups.com, yonghong.song@linux.dev Date: Wed, 11 Jun 2025 06:02:55 -0700 In-Reply-To: <68497853.050a0220.33aa0e.036a.GAE@google.com> References: <68497853.050a0220.33aa0e.036a.GAE@google.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-06-11 at 05:36 -0700, syzbot wrote: > Hello, >=20 > syzbot found the following issue on: >=20 > HEAD commit: 19a60293b992 Add linux-next specific files for 20250611 > git tree: linux-next > console+strace: https://syzkaller.appspot.com/x/log.txt?x=3D15472d7058000= 0 > kernel config: https://syzkaller.appspot.com/x/.config?x=3D76ed3656d7159= e27 > dashboard link: https://syzkaller.appspot.com/bug?extid=3Db5eb72a560b8149= a1885 > compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e0775= 7-1~exp1~20250514183223.118), Debian LLD 20.1.6 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D16af860c580= 000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=3D174db60c58000= 0 >=20 > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/c453c11565fa/dis= k-19a60293.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/4034ded42b2e/vmlinu= x-19a60293.xz > kernel image: https://storage.googleapis.com/syzbot-assets/5355903cdb8f/b= zImage-19a60293.xz >=20 > IMPORTANT: if you fix the issue, please add the following tag to the comm= it: > Reported-by: syzbot+b5eb72a560b8149a1885@syzkaller.appspotmail.com >=20 > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > BUG: KASAN: slab-use-after-free in do_check+0xb388/0xe170 kernel/bpf/veri= fier.c:19756 > Read of size 1 at addr ffff88801deeef79 by task syz-executor672/5842 >=20 > CPU: 1 UID: 0 PID: 5842 Comm: syz-executor672 Not tainted 6.16.0-rc1-next= -20250611-syzkaller #0 PREEMPT(full)=20 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS G= oogle 05/07/2025 > Call Trace: > > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:408 [inline] > print_report+0xd2/0x2b0 mm/kasan/report.c:521 > kasan_report+0x118/0x150 mm/kasan/report.c:634 > do_check+0xb388/0xe170 kernel/bpf/verifier.c:19756 > do_check_common+0x168d/0x20b0 kernel/bpf/verifier.c:22905 > do_check_main kernel/bpf/verifier.c:22996 [inline] > bpf_check+0x1381e/0x19e50 kernel/bpf/verifier.c:24162 > bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2972 > __sys_bpf+0x5f1/0x860 kernel/bpf/syscall.c:5978 > __do_sys_bpf kernel/bpf/syscall.c:6085 [inline] > __se_sys_bpf kernel/bpf/syscall.c:6083 [inline] > __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6083 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f7586cdbeb9 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 48 89 f8 48 89 f= 7 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 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffc2e683128 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7586cdbeb9 > RDX: 0000000000000094 RSI: 0000200000000840 RDI: 0000000000000005 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000006 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001 > >=20 > Allocated by task 5842: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 > poison_kmalloc_redzone mm/kasan/common.c:377 [inline] > __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394 > kasan_kmalloc include/linux/kasan.h:260 [inline] > __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359 > kmalloc_noprof include/linux/slab.h:905 [inline] > kzalloc_noprof include/linux/slab.h:1039 [inline] > do_check_common+0x13f/0x20b0 kernel/bpf/verifier.c:22798 > do_check_main kernel/bpf/verifier.c:22996 [inline] > bpf_check+0x1381e/0x19e50 kernel/bpf/verifier.c:24162 > bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2972 > __sys_bpf+0x5f1/0x860 kernel/bpf/syscall.c:5978 > __do_sys_bpf kernel/bpf/syscall.c:6085 [inline] > __se_sys_bpf kernel/bpf/syscall.c:6083 [inline] > __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6083 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f >=20 > Freed by task 5842: > kasan_save_stack mm/kasan/common.c:47 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 > kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 > poison_slab_object mm/kasan/common.c:247 [inline] > __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264 > kasan_slab_free include/linux/kasan.h:233 [inline] > slab_free_hook mm/slub.c:2381 [inline] > slab_free mm/slub.c:4643 [inline] > kfree+0x18e/0x440 mm/slub.c:4842 > push_stack+0x247/0x3c0 kernel/bpf/verifier.c:2069 > check_cond_jmp_op+0x1069/0x2340 kernel/bpf/verifier.c:16562 > do_check_insn kernel/bpf/verifier.c:19621 [inline] > do_check+0x672c/0xe170 kernel/bpf/verifier.c:19755 > do_check_common+0x168d/0x20b0 kernel/bpf/verifier.c:22905 > do_check_main kernel/bpf/verifier.c:22996 [inline] > bpf_check+0x1381e/0x19e50 kernel/bpf/verifier.c:24162 > bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2972 > __sys_bpf+0x5f1/0x860 kernel/bpf/syscall.c:5978 > __do_sys_bpf kernel/bpf/syscall.c:6085 [inline] > __se_sys_bpf kernel/bpf/syscall.c:6083 [inline] > __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6083 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f >=20 > The buggy address belongs to the object at ffff88801deeef00 > which belongs to the cache kmalloc-192 of size 192 > The buggy address is located 121 bytes inside of > freed 192-byte region [ffff88801deeef00, ffff88801deeefc0) >=20 > The buggy address belongs to the physical page: > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1dee= e > flags: 0xfff00000000000(node=3D0|zone=3D1|lastcpupid=3D0x7ff) > page_type: f5(slab) > raw: 00fff00000000000 ffff88801a4413c0 ffffea00006fca40 dead000000000004 > raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52820(= GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0= ), ts 2954361175, free_ts 2954343552 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704 > prep_new_page mm/page_alloc.c:1712 [inline] > get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669 > __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959 > alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419 > alloc_slab_page mm/slub.c:2451 [inline] > allocate_slab+0x8a/0x3b0 mm/slub.c:2619 > new_slab mm/slub.c:2673 [inline] > ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859 > __slab_alloc mm/slub.c:3949 [inline] > __slab_alloc_node mm/slub.c:4024 [inline] > slab_alloc_node mm/slub.c:4185 [inline] > __do_kmalloc_node mm/slub.c:4327 [inline] > __kmalloc_node_noprof+0x2fd/0x4e0 mm/slub.c:4334 > kmalloc_node_noprof include/linux/slab.h:932 [inline] > __vmalloc_area_node mm/vmalloc.c:3690 [inline] > __vmalloc_node_range_noprof+0x5a9/0x12f0 mm/vmalloc.c:3885 > vmalloc_huge_node_noprof+0xb3/0xf0 mm/vmalloc.c:4001 > vmalloc_huge include/linux/vmalloc.h:185 [inline] > alloc_large_system_hash+0x2b8/0x5e0 mm/mm_init.c:2515 > posixtimer_init+0x140/0x270 kernel/time/posix-timers.c:1561 > do_one_initcall+0x233/0x820 init/main.c:1274 > do_initcall_level+0x137/0x1f0 init/main.c:1336 > do_initcalls+0x69/0xd0 init/main.c:1352 > kernel_init_freeable+0x3d9/0x570 init/main.c:1584 > kernel_init+0x1d/0x1d0 init/main.c:1474 > page last free pid 1 tgid 1 stack trace: > reset_page_owner include/linux/page_owner.h:25 [inline] > free_pages_prepare mm/page_alloc.c:1248 [inline] > __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706 > __kasan_populate_vmalloc mm/kasan/shadow.c:383 [inline] > kasan_populate_vmalloc+0x18a/0x1a0 mm/kasan/shadow.c:417 > alloc_vmap_area+0xd51/0x1490 mm/vmalloc.c:2084 > __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3179 > __vmalloc_node_range_noprof+0x301/0x12f0 mm/vmalloc.c:3845 > vmalloc_huge_node_noprof+0xb3/0xf0 mm/vmalloc.c:4001 > vmalloc_huge include/linux/vmalloc.h:185 [inline] > alloc_large_system_hash+0x2b8/0x5e0 mm/mm_init.c:2515 > posixtimer_init+0x140/0x270 kernel/time/posix-timers.c:1561 > do_one_initcall+0x233/0x820 init/main.c:1274 > do_initcall_level+0x137/0x1f0 init/main.c:1336 > do_initcalls+0x69/0xd0 init/main.c:1352 > kernel_init_freeable+0x3d9/0x570 init/main.c:1584 > kernel_init+0x1d/0x1d0 init/main.c:1474 > ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >=20 > Memory state around the buggy address: > ffff88801deeee00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff88801deeee80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc > > ffff88801deeef00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff88801deeef80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc > ffff88801deef000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >=20 >=20 > --- Accessed memory is freed at an error path in push_stack(): static struct bpf_verifier_state *push_stack(...) { ... err: free_verifier_state(env->cur_state, true); // <-- KASAN points here ... } And is accessed after being freed here: static int do_check(struct bpf_verifier_env *env) { ... err =3D do_check_insn(env, &do_print_state); KASAN --> if (state->speculative && error_recoverable_with_nospec(err)) ... ... } =20 [...] Either 'state =3D env->cur_state' is needed after 'do_check_insn()' or error path should not free env->cur_state (seems logical).