===================================================== BUG: KMSAN: uninit-value in slhc_compress+0x2c5/0x2fb0 drivers/net/slip/slhc.c:251 CPU: 0 PID: 12340 Comm: syz-executor.0 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 compat_writev+0x2df/0x5a0 fs/read_write.c:1352 do_compat_pwritev64 fs/read_write.c:1401 [inline] __do_compat_sys_pwritev fs/read_write.c:1421 [inline] __se_compat_sys_pwritev+0x2bd/0x370 fs/read_write.c:1415 __ia32_compat_sys_pwritev+0x62/0x80 fs/read_write.c:1415 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline] do_fast_syscall_32+0x3bf/0x6d0 arch/x86/entry/common.c:398 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f55dd9 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:00000000f5d500cc EFLAGS: 00000296 ORIG_RAX: 000000000000014e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200002c0 RDX: 0000000000000081 RSI: 0000000000000000 RDI: 0000000000000000 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: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 compat_writev+0x2df/0x5a0 fs/read_write.c:1352 do_compat_pwritev64 fs/read_write.c:1401 [inline] __do_compat_sys_pwritev fs/read_write.c:1421 [inline] __se_compat_sys_pwritev+0x2bd/0x370 fs/read_write.c:1415 __ia32_compat_sys_pwritev+0x62/0x80 fs/read_write.c:1415 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline] do_fast_syscall_32+0x3bf/0x6d0 arch/x86/entry/common.c:398 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139 =====================================================