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KMSAN: uninit-value in attr_set_size

Status: upstream: reported C repro on 2025/10/05 23:31
Subsystems: ntfs3
[Documentation on labels]
Reported-by: syzbot+83c9dd5c0dcf6184fdbf@syzkaller.appspotmail.com
Fix commit: fs/ntfs3: fix KMSAN uninit-value in ni_create_attr_list
Patched on: [ci-upstream-linux-next-kasan-gce-root ci-upstream-rust-kasan-gce], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 47d, last: 33d
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[PATCH] fs/ntfs3: fix KMSAN uninit-value in ni_create_attr_list 3 (4) 2025/10/27 10:24
[PATCH] fs/ntfs3: fix uninitialized memory in ni_create_attr_list() 1 (1) 2025/10/07 13:40
[syzbot] [ntfs3?] KMSAN: uninit-value in attr_set_size 0 (4) 2025/10/06 15:33
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2025/10/20 00:04 37m retest repro upstream report log
2025/10/06 22:39 1h15m nirbhay.lkd@gmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 9b0d551bcc05 OK log
2025/10/06 15:33 52m nirbhay.lkd@gmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 9b0d551bcc05 OK log
2025/10/06 15:32 35m nirbhay.lkd@gmail.com patch linux-next OK log
2025/10/06 12:47 30m nirbhay.lkd@gmail.com patch upstream error

Sample crash report:
ntfs3(loop0): Failed to initialize $Extend.
=====================================================
BUG: KMSAN: uninit-value in attr_set_size+0x471b/0x6740 fs/ntfs3/attrib.c:653
 attr_set_size+0x471b/0x6740 fs/ntfs3/attrib.c:653
 ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
 ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
 ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
 iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
 ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
 splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1230
 do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
 x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 attr_set_size+0x4714/0x6740 fs/ntfs3/attrib.c:655
 ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
 ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
 ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
 iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
 ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
 splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1230
 do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
 x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 ni_create_attr_list+0x1b9b/0x1db0 fs/ntfs3/frecord.c:872
 attr_set_size+0x4174/0x6740 fs/ntfs3/attrib.c:640
 ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
 ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
 ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
 iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
 ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
 splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1230
 do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
 x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5245 [inline]
 __do_kmalloc_node mm/slub.c:5602 [inline]
 __kmalloc_noprof+0xabb/0x1b40 mm/slub.c:5615
 kmalloc_noprof include/linux/slab.h:961 [inline]
 ni_create_attr_list+0x1ca/0x1db0 fs/ntfs3/frecord.c:770
 attr_set_size+0x4174/0x6740 fs/ntfs3/attrib.c:640
 ntfs_set_size+0x222/0x330 fs/ntfs3/inode.c:861
 ntfs_extend+0x27c/0xf50 fs/ntfs3/file.c:359
 ntfs_file_write_iter+0x627/0x10d0 fs/ntfs3/file.c:1220
 iter_file_splice_write+0x12b2/0x2170 fs/splice.c:738
 ntfs_file_splice_write+0x21d/0x370 fs/ntfs3/file.c:1347
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x317/0x7d0 fs/splice.c:1161
 splice_direct_to_actor+0x99f/0x1550 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1230
 do_sendfile+0x9eb/0x1110 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x1e3/0x280 fs/read_write.c:1417
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1417
 x64_sys_call+0x36b8/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 6199 Comm: syz.0.54 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
=====================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/05 09:50 upstream 9b0d551bcc05 49379ee0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kmsan-gce-root KMSAN: uninit-value in attr_set_size
2025/10/05 23:54 upstream 9b0d551bcc05 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in attr_set_size
2025/10/05 03:24 upstream 9b0d551bcc05 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root KMSAN: uninit-value in attr_set_size
* Struck through repros no longer work on HEAD.