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KMSAN: uninit-value in bpf_skb_load_helper_32_no_cache

Status: fixed on 2020/04/15 17:19
Subsystems: net bpf
[Documentation on labels]
Fix commit: 457fed775c97 net/smc: fix leak of kernel memory to user space
First crash: 1573d, last: 1572d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in bpf_skb_load_helper_32_no_cache (2) net bpf 1 1458d 1458d 0/26 auto-closed as invalid on 2020/08/28 02:07

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:59 [inline]
BUG: KMSAN: uninit-value in __swab32p include/uapi/linux/swab.h:179 [inline]
BUG: KMSAN: uninit-value in __be32_to_cpup include/uapi/linux/byteorder/little_endian.h:82 [inline]
BUG: KMSAN: uninit-value in get_unaligned_be32 include/linux/unaligned/access_ok.h:30 [inline]
BUG: KMSAN: uninit-value in ____bpf_skb_load_helper_32 net/core/filter.c:240 [inline]
BUG: KMSAN: uninit-value in ____bpf_skb_load_helper_32_no_cache net/core/filter.c:255 [inline]
BUG: KMSAN: uninit-value in bpf_skb_load_helper_32_no_cache+0x14a/0x390 net/core/filter.c:252
CPU: 1 PID: 5262 Comm: syz-executor.5 Not tainted 5.5.0-rc5-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:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
 __fswab32 include/uapi/linux/swab.h:59 [inline]
 __swab32p include/uapi/linux/swab.h:179 [inline]
 __be32_to_cpup include/uapi/linux/byteorder/little_endian.h:82 [inline]
 get_unaligned_be32 include/linux/unaligned/access_ok.h:30 [inline]
 ____bpf_skb_load_helper_32 net/core/filter.c:240 [inline]
 ____bpf_skb_load_helper_32_no_cache net/core/filter.c:255 [inline]
 bpf_skb_load_helper_32_no_cache+0x14a/0x390 net/core/filter.c:252

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_kmalloc_large+0x73/0xc0 mm/kmsan/kmsan_hooks.c:128
 kmalloc_large_node_hook mm/slub.c:1406 [inline]
 kmalloc_large_node+0x282/0x2c0 mm/slub.c:3841
 __kmalloc_node_track_caller+0x44b/0x1200 mm/slub.c:4368
 __kmalloc_reserve net/core/skbuff.c:141 [inline]
 __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:209
 alloc_skb include/linux/skbuff.h:1049 [inline]
 netlink_dump+0x44b/0x1ab0 net/netlink/af_netlink.c:2224
 __netlink_dump_start+0xbb2/0xcf0 net/netlink/af_netlink.c:2352
 netlink_dump_start include/linux/netlink.h:233 [inline]
 smc_diag_handler_dump+0x2ba/0x300 net/smc/smc_diag.c:242
 sock_diag_rcv_msg+0x211/0x610 net/core/sock_diag.c:256
 netlink_rcv_skb+0x451/0x650 net/netlink/af_netlink.c:2477
 sock_diag_rcv+0x63/0x80 net/core/sock_diag.c:275
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x1248/0x14d0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg net/socket.c:659 [inline]
 kernel_sendmsg+0x433/0x440 net/socket.c:679
 sock_no_sendpage+0x235/0x300 net/core/sock.c:2740
 kernel_sendpage net/socket.c:3776 [inline]
 sock_sendpage+0x1e1/0x2c0 net/socket.c:937
 pipe_to_sendpage+0x38c/0x4c0 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x539/0xed0 fs/splice.c:636
 splice_from_pipe fs/splice.c:671 [inline]
 generic_splice_sendpage+0x1d5/0x2d0 fs/splice.c:844
 do_splice_from fs/splice.c:863 [inline]
 do_splice fs/splice.c:1170 [inline]
 __do_sys_splice fs/splice.c:1447 [inline]
 __se_sys_splice+0x2380/0x3350 fs/splice.c:1427
 __x64_sys_splice+0x6e/0x90 fs/splice.c:1427
 do_syscall_64+0xb8/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
=====================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/02/05 14:40 https://github.com/google/kmsan.git master 686a4f77cb0c 662cf49a .config console log report ci-upstream-kmsan-gce
2020/02/05 10:13 https://github.com/google/kmsan.git master 686a4f77cb0c 93e5e335 .config console log report ci-upstream-kmsan-gce
* Struck through repros no longer work on HEAD.