Kernel bug: KMSAN: uninit-value in bpf_prog_test_run_skb
Subsystem: bpf
Status: fixed

Crash report:
=====================================================
BUG: KMSAN: uninit-value in bpf_prog_test_run_skb+0x3091/0x3200 net/bpf/test_run.c:-1
 bpf_prog_test_run_skb+0x3091/0x3200 net/bpf/test_run.c:-1
 bpf_prog_test_run+0x5bb/0x9f0 kernel/bpf/syscall.c:4703
 __sys_bpf+0x873/0xeb0 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6272
 x64_sys_call+0x31c3/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 pskb_expand_head+0x310/0x15d0 net/core/skbuff.c:2290
 __skb_cow include/linux/skbuff.h:3853 [inline]
 skb_cow_head include/linux/skbuff.h:3887 [inline]
 bpf_skb_net_grow net/core/filter.c:3511 [inline]
 ____bpf_skb_adjust_room net/core/filter.c:3754 [inline]
 bpf_skb_adjust_room+0x103c/0x3310 net/core/filter.c:3699
 ___bpf_prog_run+0x1297/0xeba0 kernel/bpf/core.c:2037
 __bpf_prog_run512+0xc5/0x100 kernel/bpf/core.c:2333
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_test_run+0x496/0xe00 net/bpf/test_run.c:423
 bpf_prog_test_run_skb+0x2377/0x3200 net/bpf/test_run.c:1158
 bpf_prog_test_run+0x5bb/0x9f0 kernel/bpf/syscall.c:4703
 __sys_bpf+0x873/0xeb0 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6272
 x64_sys_call+0x31c3/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 skb_data_move+0x424/0x570 include/linux/skbuff.h:-1
 skb_postpush_data_move include/linux/skbuff.h:4639 [inline]
 bpf_skb_generic_push net/core/filter.c:3267 [inline]
 bpf_skb_net_hdr_push net/core/filter.c:3305 [inline]
 bpf_skb_net_grow net/core/filter.c:3542 [inline]
 ____bpf_skb_adjust_room net/core/filter.c:3754 [inline]
 bpf_skb_adjust_room+0x116c/0x3310 net/core/filter.c:3699
 ___bpf_prog_run+0x1297/0xeba0 kernel/bpf/core.c:2037
 __bpf_prog_run512+0xc5/0x100 kernel/bpf/core.c:2333
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_test_run+0x496/0xe00 net/bpf/test_run.c:423
 bpf_prog_test_run_skb+0x2377/0x3200 net/bpf/test_run.c:1158
 bpf_prog_test_run+0x5bb/0x9f0 kernel/bpf/syscall.c:4703
 __sys_bpf+0x873/0xeb0 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6272
 x64_sys_call+0x31c3/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4960 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_node_noprof+0x9e7/0x17a0 mm/slub.c:5315
 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:586
 pskb_expand_head+0x1fc/0x15d0 net/core/skbuff.c:2282
 __skb_cow include/linux/skbuff.h:3853 [inline]
 skb_cow_head include/linux/skbuff.h:3887 [inline]
 bpf_skb_net_grow net/core/filter.c:3511 [inline]
 ____bpf_skb_adjust_room net/core/filter.c:3754 [inline]
 bpf_skb_adjust_room+0x103c/0x3310 net/core/filter.c:3699
 ___bpf_prog_run+0x1297/0xeba0 kernel/bpf/core.c:2037
 __bpf_prog_run512+0xc5/0x100 kernel/bpf/core.c:2333
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 bpf_test_run+0x496/0xe00 net/bpf/test_run.c:423
 bpf_prog_test_run_skb+0x2377/0x3200 net/bpf/test_run.c:1158
 bpf_prog_test_run+0x5bb/0x9f0 kernel/bpf/syscall.c:4703
 __sys_bpf+0x873/0xeb0 kernel/bpf/syscall.c:6182
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0xa4/0xf0 kernel/bpf/syscall.c:6272
 x64_sys_call+0x31c3/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 6072 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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