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e9e14a558f8ab-435dd0691admr24239755ab.16.1764093546319; Tue, 25 Nov 2025 09:59:06 -0800 (PST) Date: Tue, 25 Nov 2025 09:59:06 -0800 In-Reply-To: <3e74d313-99df-4aeb-87b3-612f4f3634f0@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6925ee6a.a70a0220.2ea503.008e.GAE@google.com> Subject: Re: [syzbot] [batman?] KMSAN: uninit-value in skb_clone From: syzbot To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, ssranevjti@gmail.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: general protection fault in skb_clone Oops: general protection fault, probably for non-canonical address 0xdffffc000000000f: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f] CPU: 0 UID: 0 PID: 6008 Comm: syz.0.23 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:skb_clone+0xd7/0x3a0 net/core/skbuff.c:2041 Code: 03 42 80 3c 20 00 74 08 4c 89 f7 e8 f3 28 05 f9 49 83 3e 00 0f 85 a0 01 00 00 e8 94 dd 9d f8 48 8d 6b 7e 49 89 ee 49 c1 ee 03 <43> 0f b6 04 26 84 c0 0f 85 d1 01 00 00 44 0f b6 7d 00 41 83 e7 0c RSP: 0018:ffffc9000d67f200 EFLAGS: 00010207 RAX: ffffffff89223591 RBX: 0000000000000000 RCX: ffff88803362c900 RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000000 RBP: 000000000000007e R08: ffffffff8f7d0f77 R09: 1ffffffff1efa1ee R10: dffffc0000000000 R11: fffffbfff1efa1ef R12: dffffc0000000000 R13: 0000000000000820 R14: 000000000000000f R15: ffff888049098f00 FS: 00007f65d4fbc6c0(0000) GS:ffff88808d72f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f65d4fbbfc8 CR3: 0000000056473000 CR4: 0000000000352ef0 Call Trace: hsr_forward_do net/hsr/hsr_forward.c:-1 [inline] hsr_forward_skb+0x1013/0x2860 net/hsr/hsr_forward.c:745 hsr_handle_frame+0x6ce/0xa70 net/hsr/hsr_slave.c:84 __netif_receive_skb_core+0x10b9/0x4380 net/core/dev.c:5966 __netif_receive_skb_one_core net/core/dev.c:6077 [inline] __netif_receive_skb+0x72/0x380 net/core/dev.c:6192 netif_receive_skb_internal net/core/dev.c:6278 [inline] netif_receive_skb+0x1cb/0x790 net/core/dev.c:6337 tun_rx_batched+0x1b9/0x730 drivers/net/tun.c:1485 tun_get_user+0x2b65/0x3e90 drivers/net/tun.c:1953 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1999 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f65d598e1ff Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48 RSP: 002b:00007f65d4fbc000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f65d5be6180 RCX: 00007f65d598e1ff RDX: 000000000000003e RSI: 0000200000000500 RDI: 00000000000000c8 RBP: 00007f65d4fbc090 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000003e R11: 0000000000000293 R12: 0000000000000001 R13: 00007f65d5be6218 R14: 00007f65d5be6180 R15: 00007ffeb6e64a58 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:skb_clone+0xd7/0x3a0 net/core/skbuff.c:2041 Code: 03 42 80 3c 20 00 74 08 4c 89 f7 e8 f3 28 05 f9 49 83 3e 00 0f 85 a0 01 00 00 e8 94 dd 9d f8 48 8d 6b 7e 49 89 ee 49 c1 ee 03 <43> 0f b6 04 26 84 c0 0f 85 d1 01 00 00 44 0f b6 7d 00 41 83 e7 0c RSP: 0018:ffffc9000d67f200 EFLAGS: 00010207 RAX: ffffffff89223591 RBX: 0000000000000000 RCX: ffff88803362c900 RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000000 RBP: 000000000000007e R08: ffffffff8f7d0f77 R09: 1ffffffff1efa1ee R10: dffffc0000000000 R11: fffffbfff1efa1ef R12: dffffc0000000000 R13: 0000000000000820 R14: 000000000000000f R15: ffff888049098f00 FS: 00007f65d4fbc6c0(0000) GS:ffff88808d72f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f65d4fbbfc8 CR3: 0000000056473000 CR4: 0000000000352ef0 ---------------- Code disassembly (best guess): 0: 03 42 80 add -0x80(%rdx),%eax 3: 3c 20 cmp $0x20,%al 5: 00 74 08 4c add %dh,0x4c(%rax,%rcx,1) 9: 89 f7 mov %esi,%edi b: e8 f3 28 05 f9 call 0xf9052903 10: 49 83 3e 00 cmpq $0x0,(%r14) 14: 0f 85 a0 01 00 00 jne 0x1ba 1a: e8 94 dd 9d f8 call 0xf89dddb3 1f: 48 8d 6b 7e lea 0x7e(%rbx),%rbp 23: 49 89 ee mov %rbp,%r14 26: 49 c1 ee 03 shr $0x3,%r14 * 2a: 43 0f b6 04 26 movzbl (%r14,%r12,1),%eax <-- trapping instruction 2f: 84 c0 test %al,%al 31: 0f 85 d1 01 00 00 jne 0x208 37: 44 0f b6 7d 00 movzbl 0x0(%rbp),%r15d 3c: 41 83 e7 0c and $0xc,%r15d Tested on: commit: 30f09200 Merge tag 'arm64-fixes' of git://git.kernel.o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15e6cf42580000 kernel config: https://syzkaller.appspot.com/x/.config?x=a1db0fea040c2a9f dashboard link: https://syzkaller.appspot.com/bug?extid=2fa344348a579b779e05 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 patch: https://syzkaller.appspot.com/x/patch.diff?x=1281a612580000