Re: [syzbot] [exfat?] KMSAN: uninit-value in __exfat_get_dentry_set

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in __exfat_get_dentry_set

loop0: detected capacity change from 0 to 256
exFAT-fs (loop0): failed to load upcase table (idx : 0x00010000, chksum : 0x726052d3, utbl_chksum : 0xe619d30d)
=====================================================
BUG: KMSAN: uninit-value in __exfat_get_dentry_set+0x10db/0x14d0 fs/exfat/dir.c:805
 __exfat_get_dentry_set+0x10db/0x14d0 fs/exfat/dir.c:805
 exfat_get_dentry_set+0x58/0xec0 fs/exfat/dir.c:860
 __exfat_write_inode+0x3c1/0xe30 fs/exfat/inode.c:46
 __exfat_truncate+0x7f3/0xbb0 fs/exfat/file.c:211
 exfat_truncate+0xee/0x2a0 fs/exfat/file.c:257
 exfat_write_failed fs/exfat/inode.c:421 [inline]
 exfat_direct_IO+0x5a3/0x900 fs/exfat/inode.c:485
 generic_file_direct_write+0x275/0x6a0 mm/filemap.c:3977
 __generic_file_write_iter+0x242/0x460 mm/filemap.c:4141
 exfat_file_write_iter+0x894/0xfb0 fs/exfat/file.c:598
 do_iter_readv_writev+0x88a/0xa30
 vfs_writev+0x56a/0x14f0 fs/read_write.c:1064
 do_pwritev fs/read_write.c:1165 [inline]
 __do_sys_pwritev2 fs/read_write.c:1224 [inline]
 __se_sys_pwritev2+0x280/0x470 fs/read_write.c:1215
 __x64_sys_pwritev2+0x11f/0x1a0 fs/read_write.c:1215
 x64_sys_call+0x2edb/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:329
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 memcpy_to_iter lib/iov_iter.c:65 [inline]
 iterate_bvec include/linux/iov_iter.h:123 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:304 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 _copy_to_iter+0xe53/0x2b30 lib/iov_iter.c:185
 copy_page_to_iter+0x419/0x880 lib/iov_iter.c:362
 shmem_file_read_iter+0xa09/0x12b0 mm/shmem.c:3167
 do_iter_readv_writev+0x88a/0xa30
 vfs_iter_read+0x278/0x760 fs/read_write.c:923
 lo_read_simple drivers/block/loop.c:283 [inline]
 do_req_filebacked drivers/block/loop.c:516 [inline]
 loop_handle_cmd drivers/block/loop.c:1910 [inline]
 loop_process_work+0x20fc/0x3750 drivers/block/loop.c:1945
 loop_workfn+0x48/0x60 drivers/block/loop.c:1969
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was stored to memory at:
 memcpy_from_iter lib/iov_iter.c:73 [inline]
 iterate_bvec include/linux/iov_iter.h:123 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:304 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 __copy_from_iter lib/iov_iter.c:249 [inline]
 copy_page_from_iter_atomic+0x12b7/0x3100 lib/iov_iter.c:481
 copy_folio_from_iter_atomic include/linux/uio.h:201 [inline]
 generic_perform_write+0x8d1/0x1080 mm/filemap.c:4066
 shmem_file_write_iter+0x2ba/0x2f0 mm/shmem.c:3221
 do_iter_readv_writev+0x88a/0xa30
 vfs_iter_write+0x44d/0xd40 fs/read_write.c:988
 lo_write_bvec drivers/block/loop.c:243 [inline]
 lo_write_simple drivers/block/loop.c:264 [inline]
 do_req_filebacked drivers/block/loop.c:511 [inline]
 loop_handle_cmd drivers/block/loop.c:1910 [inline]
 loop_process_work+0x15e6/0x3750 drivers/block/loop.c:1945
 loop_workfn+0x48/0x60 drivers/block/loop.c:1969
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
 __alloc_pages_noprof+0x9a7/0xe00 mm/page_alloc.c:4756
 alloc_pages_mpol_noprof+0x299/0x990 mm/mempolicy.c:2265
 alloc_pages_noprof mm/mempolicy.c:2345 [inline]
 folio_alloc_noprof+0x1db/0x310 mm/mempolicy.c:2352
 filemap_alloc_folio_noprof+0xa6/0x440 mm/filemap.c:1010
 __filemap_get_folio+0xac4/0x1550 mm/filemap.c:1952
 block_write_begin+0x6e/0x2b0 fs/buffer.c:2226
 exfat_write_begin+0xfb/0x400 fs/exfat/inode.c:434
 exfat_extend_valid_size fs/exfat/file.c:553 [inline]
 exfat_file_write_iter+0x474/0xfb0 fs/exfat/file.c:588
 do_iter_readv_writev+0x88a/0xa30
 vfs_writev+0x56a/0x14f0 fs/read_write.c:1064
 do_pwritev fs/read_write.c:1165 [inline]
 __do_sys_pwritev2 fs/read_write.c:1224 [inline]
 __se_sys_pwritev2+0x280/0x470 fs/read_write.c:1215
 __x64_sys_pwritev2+0x11f/0x1a0 fs/read_write.c:1215
 x64_sys_call+0x2edb/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:329
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 5987 Comm: syz.0.15 Not tainted 6.12.0-rc2-syzkaller-00291-g09f6b0c8904b-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
=====================================================


Tested on:

commit:         09f6b0c8 Merge tag 'linux_kselftest-fixes-6.12-rc3' of..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=121adfd0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=981fe2ff8a1e457a
dashboard link: https://syzkaller.appspot.com/bug?extid=01218003be74b5e1213a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14b2dfd0580000