===================================================== BUG: KMSAN: uninit-value in slhc_compress+0x2c5/0x2fb0 drivers/net/slip/slhc.c:251 CPU: 1 PID: 2045 Comm: syz-executor.1 Not tainted 5.7.0-rc4-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:121 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215 slhc_compress+0x2c5/0x2fb0 drivers/net/slip/slhc.c:251 ppp_send_frame drivers/net/ppp/ppp_generic.c:1637 [inline] __ppp_xmit_process+0x1902/0x2970 drivers/net/ppp/ppp_generic.c:1495 ppp_xmit_process+0x147/0x2f0 drivers/net/ppp/ppp_generic.c:1516 ppp_write+0x6bb/0x790 drivers/net/ppp/ppp_generic.c:512 do_loop_readv_writev fs/read_write.c:718 [inline] do_iter_write+0xa0a/0xdc0 fs/read_write.c:1001 vfs_writev fs/read_write.c:1072 [inline] do_pwritev+0x487/0x7d0 fs/read_write.c:1169 __do_sys_pwritev fs/read_write.c:1216 [inline] __se_sys_pwritev+0xc6/0xe0 fs/read_write.c:1211 __x64_sys_pwritev+0x62/0x80 fs/read_write.c:1211 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45ca69 Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fb4a3fe2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000128 RAX: ffffffffffffffda RBX: 00000000004facc0 RCX: 000000000045ca69 RDX: 0000000000000003 RSI: 0000000020000480 RDI: 0000000000000003 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000879 R14: 00000000004cb58e R15: 00007fb4a3fe36d4 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:80 slab_alloc_node mm/slub.c:2802 [inline] __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4436 __kmalloc_reserve net/core/skbuff.c:142 [inline] __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1083 [inline] ppp_write+0x115/0x790 drivers/net/ppp/ppp_generic.c:500 do_loop_readv_writev fs/read_write.c:718 [inline] do_iter_write+0xa0a/0xdc0 fs/read_write.c:1001 vfs_writev fs/read_write.c:1072 [inline] do_pwritev+0x487/0x7d0 fs/read_write.c:1169 __do_sys_pwritev fs/read_write.c:1216 [inline] __se_sys_pwritev+0xc6/0xe0 fs/read_write.c:1211 __x64_sys_pwritev+0x62/0x80 fs/read_write.c:1211 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x44/0xa9 =====================================================