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BUG: KMSAN: uninit-value in vb2_mmap+0xb2f/0xc90 drivers/media/common/videobuf2/videobuf2-core.c:2173
CPU: 0 PID: 29571 Comm: syz-executor4 Not tainted 4.20.0-rc7+ #4
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+0x173/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x12e/0x2a0 mm/kmsan/kmsan.c:613
 __msan_warning+0x82/0xf0 mm/kmsan/kmsan_instr.c:313
 vb2_mmap+0xb2f/0xc90 drivers/media/common/videobuf2/videobuf2-core.c:2173
 vb2_fop_mmap+0xa9/0xd0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1004
 v4l2_mmap+0x212/0x400 drivers/media/v4l2-core/v4l2-dev.c:401
 call_mmap include/linux/fs.h:1862 [inline]
 mmap_region+0x2d98/0x3aa0 mm/mmap.c:1786
 do_mmap+0x183e/0x1e70 mm/mmap.c:1559
 do_mmap_pgoff include/linux/mm.h:2328 [inline]
 vm_mmap_pgoff+0x313/0x430 mm/util.c:350
 ksys_mmap_pgoff+0xa2e/0xae0 mm/mmap.c:1609
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap+0x172/0x1a0 arch/x86/kernel/sys_x86_64.c:91
 __x64_sys_mmap+0x69/0x90 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457ec9
Code: 6d 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fdacffbcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000457ec9
RDX: fffffffffffffffd RSI: 0000000000002000 RDI: 0000000020ffe000
RBP: 000000000073bf00 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 00007fdacffbd6d4
R13: 00000000004c3b56 R14: 00000000004d6910 R15: 00000000ffffffff

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:204 [inline]
 kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:158
 kmsan_kmalloc+0xa6/0x130 mm/kmsan/kmsan_hooks.c:176
 kmsan_slab_alloc+0xe/0x10 mm/kmsan/kmsan_hooks.c:185
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2759 [inline]
 __kmalloc_node_track_caller+0xe18/0x1030 mm/slub.c:4383
 __kmalloc_reserve net/core/skbuff.c:137 [inline]
 __alloc_skb+0x309/0xa20 net/core/skbuff.c:205
 alloc_skb_fclone include/linux/skbuff.h:1040 [inline]
 sk_stream_alloc_skb+0x177/0xcb0 net/ipv4/tcp.c:874
 tcp_sendmsg_locked+0x2b1a/0x6be0 net/ipv4/tcp.c:1286
 tcp_sendmsg+0xb2/0x100 net/ipv4/tcp.c:1443
 inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 sock_write_iter+0x3f4/0x4d0 net/socket.c:900
 call_write_iter include/linux/fs.h:1857 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x888/0xb70 fs/read_write.c:487
 vfs_write+0x478/0x8d0 fs/read_write.c:549
 ksys_write fs/read_write.c:598 [inline]
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write+0x17a/0x370 fs/read_write.c:607
 __x64_sys_write+0x4a/0x70 fs/read_write.c:607
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
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