Hello,

syzbot found the following crash on:

HEAD commit: 8bbbc5cf kmsan: don't compile memmove git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=15471109e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=cd0e9a6b0e555cc3 dashboard link: https://syzkaller.appspot.com/bug?extid=0adb190024de0a0e265b compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) userspace arch: i386 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1247c109e00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1349a779e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+0adb190024de0a0e265b@syzkaller.appspotmail.com

===================================================== BUG: KMSAN: uninit-value in batadv_get_vid+0x1fd/0x340 net/batman-adv/main.c:650 CPU: 0 PID: 12317 Comm: syz-executor026 Not tainted 5.6.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c9/0x220 lib/dump_stack.c:118 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215 batadv_get_vid+0x1fd/0x340 net/batman-adv/main.c:650 batadv_interface_tx+0x30a/0x2450 net/batman-adv/soft-interface.c:212 __netdev_start_xmit include/linux/netdevice.h:4524 [inline] netdev_start_xmit include/linux/netdevice.h:4538 [inline] xmit_one net/core/dev.c:3470 [inline] dev_hard_start_xmit+0x531/0xab0 net/core/dev.c:3486 __dev_queue_xmit+0x37de/0x4220 net/core/dev.c:4063 dev_queue_xmit+0x4b/0x60 net/core/dev.c:4096 __bpf_tx_skb net/core/filter.c:2061 [inline] __bpf_redirect_common net/core/filter.c:2100 [inline] __bpf_redirect+0x11d5/0x1440 net/core/filter.c:2107 ____bpf_clone_redirect net/core/filter.c:2140 [inline] bpf_clone_redirect+0x466/0x620 net/core/filter.c:2112 bpf_prog_bb15b996d00816f9+0x7a4/0x1000 bpf_dispatcher_nopfunc include/linux/bpf.h:521 [inline] bpf_test_run+0x60c/0xe50 net/bpf/test_run.c:48 bpf_prog_test_run_skb+0xcab/0x24a0 net/bpf/test_run.c:388 bpf_prog_test_run kernel/bpf/syscall.c:2572 [inline] __do_sys_bpf+0xa684/0x13510 kernel/bpf/syscall.c:3414 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline] __ia32_sys_bpf+0xdb/0x120 kernel/bpf/syscall.c:3355 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline] do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7fc8d99 Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000ff9adc0c EFLAGS: 00000246 ORIG_RAX: 0000000000000165 RAX: ffffffffffffffda RBX: 000000000000000a RCX: 0000000020000280 RDX: 0000000000000040 RSI: 0000000000000000 RDI: 000000000000005b RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline] kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82 slab_alloc_node mm/slub.c:2793 [inline] __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4401 __kmalloc_reserve net/core/skbuff.c:142 [inline] pskb_expand_head+0x20b/0x1b00 net/core/skbuff.c:1629 skb_ensure_writable+0x3ea/0x490 net/core/skbuff.c:5453 __bpf_try_make_writable net/core/filter.c:1635 [inline] bpf_try_make_writable net/core/filter.c:1641 [inline] bpf_try_make_head_writable net/core/filter.c:1649 [inline] ____bpf_clone_redirect net/core/filter.c:2134 [inline] bpf_clone_redirect+0x251/0x620 net/core/filter.c:2112 bpf_prog_bb15b996d00816f9+0x7a4/0x1000 bpf_dispatcher_nopfunc include/linux/bpf.h:521 [inline] bpf_test_run+0x60c/0xe50 net/bpf/test_run.c:48 bpf_prog_test_run_skb+0xcab/0x24a0 net/bpf/test_run.c:388 bpf_prog_test_run kernel/bpf/syscall.c:2572 [inline] __do_sys_bpf+0xa684/0x13510 kernel/bpf/syscall.c:3414 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline] __ia32_sys_bpf+0xdb/0x120 kernel/bpf/syscall.c:3355 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline] do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139 =====================================================

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