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BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x9c/0xb0 mm/kmsan/kmsan_hooks.c:249
CPU: 1 PID: 4831 Comm: systemd-udevd Not tainted 5.10.0-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+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 kmsan_internal_check_memory+0x202/0x520 mm/kmsan/kmsan.c:402
 kmsan_copy_to_user+0x9c/0xb0 mm/kmsan/kmsan_hooks.c:249
 instrument_copy_to_user include/linux/instrumented.h:121 [inline]
 copyout lib/iov_iter.c:147 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:222 [inline]
 copy_page_to_iter+0xa7c/0x21b0 lib/iov_iter.c:929
 generic_file_buffered_read+0x4548/0x6640 mm/filemap.c:2332
 generic_file_read_iter+0x1c2/0xcf0 mm/filemap.c:2535
 blkdev_read_iter+0x1fe/0x2c0 fs/block_dev.c:1925
 call_read_iter include/linux/fs.h:1897 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x13c1/0x1590 fs/read_write.c:496
 ksys_read+0x2af/0x4d0 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read+0x92/0xb0 fs/read_write.c:642
 __x64_sys_read+0x4a/0x70 fs/read_write.c:642
 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f45123cc210
Code: 73 01 c3 48 8b 0d 98 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d b9 c1 20 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 4e fc ff ff 48 89 04 24
RSP: 002b:00007ffd51581688 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 000056037a552cc0 RCX: 00007f45123cc210
RDX: 0000000000000018 RSI: 000056037a552ce8 RDI: 000000000000000f
RBP: 000056037a550b40 R08: 0000000000000000 R09: 0000000000000050
R10: 000056037a552cd8 R11: 0000000000000246 R12: 00000000001e0000
R13: 00000000001e0018 R14: 000056037a550b90 R15: 0000000000000018

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:121
 kmsan_alloc_page+0xd3/0x1f0 mm/kmsan/kmsan_shadow.c:274
 __alloc_pages_nodemask+0x84e/0xfb0 mm/page_alloc.c:4989
 alloc_pages_current+0x79b/0xb40 mm/mempolicy.c:2271
 alloc_pages include/linux/gfp.h:547 [inline]
 __page_cache_alloc mm/filemap.c:977 [inline]
 pagecache_get_page+0x1122/0x2050 mm/filemap.c:1828
 find_or_create_page include/linux/pagemap.h:404 [inline]
 grow_dev_page+0x1aa/0xde0 fs/buffer.c:974
 grow_buffers fs/buffer.c:1043 [inline]
 __getblk_slow fs/buffer.c:1070 [inline]
 __getblk_gfp+0x464/0x6a0 fs/buffer.c:1354
 sb_getblk_gfp include/linux/buffer_head.h:332 [inline]
 ext4_ext_split fs/ext4/extents.c:1077 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1368 [inline]
 ext4_ext_insert_extent+0x3f2b/0x9430 fs/ext4/extents.c:2054
 ext4_ext_map_blocks+0x5cb3/0x7650 fs/ext4/extents.c:4259
 ext4_map_blocks+0x1b4b/0x3860 fs/ext4/inode.c:628
 _ext4_get_block+0x2de/0xa40 fs/ext4/inode.c:784
 ext4_get_block_unwritten+0x9d/0xb0 fs/ext4/inode.c:815
 ext4_block_write_begin+0xb19/0x2220 fs/ext4/inode.c:1068
 ext4_write_begin+0xb9b/0x2d10 fs/ext4/ext4_jbd2.h:506
 ext4_da_write_begin+0x6ae/0x2080 fs/ext4/inode.c:2952
 generic_perform_write+0x479/0xb20 mm/filemap.c:3311
 ext4_buffered_write_iter+0x8e2/0xc60 fs/ext4/file.c:270
 ext4_file_write_iter+0xf3a/0x3690 fs/ext4/file.c:503
 do_iter_readv_writev+0xa9e/0xc30 include/linux/fs.h:1897
 do_iter_write+0x371/0x1090 fs/read_write.c:866
 vfs_writev fs/read_write.c:939 [inline]
 do_pwritev+0x551/0xb80 fs/read_write.c:1036
 __do_compat_sys_pwritev fs/read_write.c:1160 [inline]
 __se_compat_sys_pwritev+0xef/0x100 fs/read_write.c:1154
 __ia32_compat_sys_pwritev+0x62/0x80 fs/read_write.c:1154
 do_syscall_32_irqs_on arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x102/0x160 arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Bytes 8-11 of 24 are uninitialized
Memory access of size 24 starts at ffff888166974000
Data copied to user address 000056037a552ce8
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