RSP: 002b:00000000f58615cc EFLAGS: 00000296 ORIG_RAX: 000000000000014e
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000080
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
=====================================================
BUG: KMSAN: uninit-value in ppp_send_frame+0x28d/0x27c0 drivers/net/ppp/ppp_generic.c:1740
 ppp_send_frame+0x28d/0x27c0 drivers/net/ppp/ppp_generic.c:1740
 __ppp_xmit_process+0x23e/0x4b0 drivers/net/ppp/ppp_generic.c:1640
 ppp_xmit_process+0x1fe/0x480 drivers/net/ppp/ppp_generic.c:1661
 ppp_write+0x5cb/0x5e0 drivers/net/ppp/ppp_generic.c:513
 do_iter_write+0xb0c/0x1500 fs/read_write.c:853
 vfs_writev fs/read_write.c:924 [inline]
 do_pwritev+0x647/0xc60 fs/read_write.c:1021
 __do_compat_sys_pwritev fs/read_write.c:1145 [inline]
 __se_compat_sys_pwritev fs/read_write.c:1139 [inline]
 __ia32_compat_sys_pwritev+0x166/0x1c0 fs/read_write.c:1139
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:524 [inline]
 slab_alloc_node mm/slub.c:3251 [inline]
 __kmalloc_node_track_caller+0xe0c/0x1510 mm/slub.c:4974
 kmalloc_reserve net/core/skbuff.c:354 [inline]
 __alloc_skb+0x545/0xf90 net/core/skbuff.c:426
 alloc_skb include/linux/skbuff.h:1126 [inline]
 ppp_write+0x11d/0x5e0 drivers/net/ppp/ppp_generic.c:501
 do_iter_write+0xb0c/0x1500 fs/read_write.c:853
 vfs_writev fs/read_write.c:924 [inline]
 do_pwritev+0x647/0xc60 fs/read_write.c:1021
 __do_compat_sys_pwritev fs/read_write.c:1145 [inline]
 __se_compat_sys_pwritev fs/read_write.c:1139 [inline]
 __ia32_compat_sys_pwritev+0x166/0x1c0 fs/read_write.c:1139
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

CPU: 0 PID: 22372 Comm: syz-executor.1 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================