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BUG: KASAN: slab-out-of-bounds in parse_build_id_buf+0x29e/0x350 lib/buildid.c:45
Write of size 20 at addr ffff888079bf52f4 by task syz.0.20/5946

CPU: 1 PID: 5946 Comm: syz.0.20 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x241/0x290 mm/kasan/generic.c:187
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 parse_build_id_buf+0x29e/0x350 lib/buildid.c:45
 parse_build_id lib/buildid.c:72 [inline]
 get_build_id_64+0x18d/0x230 lib/buildid.c:133
 build_id_parse+0x297/0x560 lib/buildid.c:188
 stack_map_get_build_id_offset+0x349/0x720 kernel/bpf/stackmap.c:159
 __bpf_get_stackid+0x564/0x900 kernel/bpf/stackmap.c:247
 ____bpf_get_stackid_pe kernel/bpf/stackmap.c:374 [inline]
 bpf_get_stackid_pe+0x2f0/0x410 kernel/bpf/stackmap.c:331
 bpf_prog_12712c88fd19bd5b+0x29/0x2d
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:617 [inline]
 bpf_prog_run include/linux/filter.h:624 [inline]
 bpf_overflow_handler+0x1fc/0x510 kernel/events/core.c:10584
 __perf_event_overflow+0x461/0x660 kernel/events/core.c:9720
 perf_swevent_overflow kernel/events/core.c:9803 [inline]
 perf_swevent_event+0x319/0x570 kernel/events/core.c:9854
 do_perf_sw_event kernel/events/core.c:9967 [inline]
 ___perf_sw_event+0x4ab/0x730 kernel/events/core.c:9998
 __perf_sw_event+0x139/0x270 kernel/events/core.c:10010
 perf_sw_event include/linux/perf_event.h:1442 [inline]
 do_user_addr_fault+0x1242/0x12d0 arch/x86/mm/fault.c:1278
 handle_page_fault arch/x86/mm/fault.c:1463 [inline]
 exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7fff659fea21
Code: 48 89 c2 eb a7 4c 29 d2 48 0f ba e2 3e 0f 82 ad 00 00 00 48 bf ff ff ff ff ff ff ff 7f 48 21 fa 49 0f af d1 48 01 c2 48 d3 ea <48> 89 55 c0 31 c0 48 81 fa 00 ca 9a 3b 72 1c 31 c9 48 81 c2 00 36
RSP: 002b:00007f7029103ff0 EFLAGS: 00010203
RAX: 00202a5477882dec RBX: 00007fff659fa0b0 RCX: 0000000000000018
RDX: 00000000203df22a RSI: 00007f70291040b0 RDI: 7fffffffffffffff
RBP: 00007f7029104030 R08: 0000000000000068 R09: 0000000000745d1e
R10: 000000395adeb393 R11: 0000000000004d3a R12: 0000000000000010
R13: 00007f7028426038 R14: 00007fff659fa080 R15: 0000000000004d3a
 </TASK>

Allocated by task 5946:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc_node+0xb6/0x240 mm/slab_common.c:1014
 kmalloc_node include/linux/slab.h:620 [inline]
 __bpf_map_area_alloc kernel/bpf/syscall.c:303 [inline]
 bpf_map_area_alloc+0x5e/0x110 kernel/bpf/syscall.c:316
 prealloc_elems_and_freelist+0x86/0x1c0 kernel/bpf/stackmap.c:51
 stack_map_alloc+0x32b/0x4b0 kernel/bpf/stackmap.c:114
 map_create+0x877/0x12f0 kernel/bpf/syscall.c:1247
 __sys_bpf+0x651/0x890 kernel/bpf/syscall.c:5473
 __do_sys_bpf kernel/bpf/syscall.c:5595 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5593 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5593
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888079bf5200
 which belongs to the cache kmalloc-cg-256 of size 256
The buggy address is located 4 bytes to the right of
 allocated 240-byte region [ffff888079bf5200, ffff888079bf52f0)

The buggy address belongs to the physical page:
page:ffffea0001e6fd00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x79bf4
head:ffffea0001e6fd00 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88803084e501
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c4f000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000001ffffffff ffff88803084e501
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5892, tgid 5892 (syz-executor), ts 98981163260, free_ts 98416673138
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_slab_page+0x5d/0x180 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x11f/0x250 mm/slub.c:3534
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 alloc_mnt_ns+0xaf/0x3b0 fs/namespace.c:3769
 copy_mnt_ns+0xd0/0x8f0 fs/namespace.c:3814
 create_new_namespaces+0xd3/0x700 kernel/nsproxy.c:78
 unshare_nsproxy_namespaces+0x11a/0x160 kernel/nsproxy.c:228
 ksys_unshare+0x4fa/0x8f0 kernel/fork.c:3444
 __do_sys_unshare kernel/fork.c:3518 [inline]
 __se_sys_unshare kernel/fork.c:3516 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3516
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x194/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node+0xa6/0x240 mm/slab_common.c:1014
 kmalloc_node include/linux/slab.h:620 [inline]
 __vmalloc_area_node mm/vmalloc.c:3175 [inline]
 __vmalloc_node_range+0x598/0x1320 mm/vmalloc.c:3370
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3c8/0x800 kernel/fork.c:1126
 copy_process+0x5a6/0x3da0 kernel/fork.c:2339
 kernel_clone+0x24b/0x8a0 kernel/fork.c:2919
 __do_sys_clone kernel/fork.c:3062 [inline]
 __se_sys_clone kernel/fork.c:3046 [inline]
 __x64_sys_clone+0x1b7/0x230 kernel/fork.c:3046

Memory state around the buggy address:
 ffff888079bf5180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888079bf5200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888079bf5280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
                                                             ^
 ffff888079bf5300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888079bf5380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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