KMSAN: uninit-value in slhc

KMSAN: uninit-value in slhc_compress (2)
Status: upstream: reported C repro on 2020/06/06 06:53
Reported-by: syzbot+801c60509310ac8083dd@syzkaller.appspotmail.com
First crash: 383d, last: 326d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KMSAN: uninit-value in slhc_compress	C			3	473d	473d	17/22	fixed on 2020/04/15 17:19

Patch testing requests:
Created	Duration	User	Patch	Repo	Result
2020/10/31 23:49	14m	anant.thazhemadam@gmail.com		https://github.com/google/kmsan.git master	report log

Sample crash report:

=====================================================
BUG: KMSAN: uninit-value in slhc_compress+0x2c5/0x2fb0 drivers/net/slip/slhc.c:251
CPU: 0 PID: 9204 Comm: syz-executor789 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: 0033:0x4412f9
Code: e8 fc ab 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd3ec8cf78 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004412f9
RDX: 0000000000000003 RSI: 0000000020000480 RDI: 0000000000000003
RBP: 0000000000014688 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402120
R13: 00000000004021b0 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
 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
=====================================================

Crashes (21):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci-upstream-kmsan-gce	2020/06/09 21:21	https://github.com/google/kmsan.git master	f0d5ec90	092934c1	.config	log	report	syz	C
ci-upstream-kmsan-gce	2020/07/29 00:31	https://github.com/google/kmsan.git master	93f54a72	cb93dc6a	.config	log	report
ci-upstream-kmsan-gce	2020/07/25 23:38	https://github.com/google/kmsan.git master	93f54a72	1f7cc1ca	.config	log	report
ci-upstream-kmsan-gce	2020/07/24 23:43	https://github.com/google/kmsan.git master	93f54a72	554af388	.config	log	report
ci-upstream-kmsan-gce	2020/07/24 02:30	https://github.com/google/kmsan.git master	93f54a72	70c104a1	.config	log	report
ci-upstream-kmsan-gce	2020/07/24 02:21	https://github.com/google/kmsan.git master	93f54a72	70c104a1	.config	log	report
ci-upstream-kmsan-gce	2020/06/27 18:23	https://github.com/google/kmsan.git master	f0d5ec90	ffec44b5	.config	log	report
ci-upstream-kmsan-gce	2020/06/27 18:23	https://github.com/google/kmsan.git master	f0d5ec90	ffec44b5	.config	log	report
ci-upstream-kmsan-gce	2020/06/27 18:02	https://github.com/google/kmsan.git master	f0d5ec90	ffec44b5	.config	log	report
ci-upstream-kmsan-gce	2020/06/26 05:25	https://github.com/google/kmsan.git master	f0d5ec90	aea82c00	.config	log	report
ci-upstream-kmsan-gce	2020/06/23 17:09	https://github.com/google/kmsan.git master	f0d5ec90	54566aff	.config	log	report
ci-upstream-kmsan-gce	2020/06/23 17:09	https://github.com/google/kmsan.git master	f0d5ec90	54566aff	.config	log	report
ci-upstream-kmsan-gce	2020/06/23 17:08	https://github.com/google/kmsan.git master	f0d5ec90	54566aff	.config	log	report
ci-upstream-kmsan-gce	2020/06/23 17:08	https://github.com/google/kmsan.git master	f0d5ec90	54566aff	.config	log	report
ci-upstream-kmsan-gce	2020/06/09 20:23	https://github.com/google/kmsan.git master	f0d5ec90	092934c1	.config	log	report
ci-upstream-kmsan-gce	2020/06/01 21:49	https://github.com/google/kmsan.git master	f0d5ec90	a0331e89	.config	log	report
ci-upstream-kmsan-gce-386	2020/07/24 23:41	https://github.com/google/kmsan.git master	93f54a72	554af388	.config	log	report
ci-upstream-kmsan-gce-386	2020/07/24 02:37	https://github.com/google/kmsan.git master	93f54a72	70c104a1	.config	log	report
ci-upstream-kmsan-gce-386	2020/07/24 02:23	https://github.com/google/kmsan.git master	93f54a72	70c104a1	.config	log	report
ci-upstream-kmsan-gce-386	2020/07/09 00:12	https://github.com/google/kmsan.git master	f0d5ec90	bc238812	.config	log	report
ci-upstream-kmsan-gce-386	2020/06/09 10:22	https://github.com/google/kmsan.git master	f0d5ec90	0d60b78a	.config	log	report