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Date: Thu, 28 Dec 2023 16:08:04 -0800
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Subject: Re: [syzbot] [hfs?] KMSAN: uninit-value in __hfsplus_ext_cache_extent
From: syzbot <syzbot+55ad87f38795d6787521@syzkaller.appspotmail.com>
To: eadavis@qq.com, linux-kernel@vger.kernel.org, 
	syzkaller-bugs@googlegroups.com
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Hello,

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

loop0: detected capacity change from 0 to 1024
=====================================================
BUG: KMSAN: uninit-value in __hfsplus_ext_read_extent fs/hfsplus/extents.c:170 [inline]
BUG: KMSAN: uninit-value in __hfsplus_ext_cache_extent+0x851/0x960 fs/hfsplus/extents.c:191
 __hfsplus_ext_read_extent fs/hfsplus/extents.c:170 [inline]
 __hfsplus_ext_cache_extent+0x851/0x960 fs/hfsplus/extents.c:191
 hfsplus_file_truncate+0x730/0xf50 fs/hfsplus/extents.c:598
 hfsplus_write_failed+0xab/0x100 fs/hfsplus/inode.c:42
 hfsplus_write_begin+0x12e/0x130 fs/hfsplus/inode.c:56
 generic_perform_write+0x3f5/0xc40 mm/filemap.c:3918
 __generic_file_write_iter+0x20a/0x460 mm/filemap.c:4013
 generic_file_write_iter+0x103/0x5b0 mm/filemap.c:4039
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x8ef/0x1490 fs/read_write.c:584
 ksys_write+0x20f/0x4c0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x93/0xd0 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Local variable fd created at:
 hfsplus_file_truncate+0x5d/0xf50 fs/hfsplus/extents.c:547
 hfsplus_write_failed+0xab/0x100 fs/hfsplus/inode.c:42

CPU: 1 PID: 5490 Comm: syz-executor.0 Not tainted 6.7.0-rc7-syzkaller-00003-gfbafc3e621c3-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
=====================================================


Tested on:

commit:         fbafc3e6 Merge tag 'for_linus' of git://git.kernel.org..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=14922dcee80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e0c7078a6b901aa3
dashboard link: https://syzkaller.appspot.com/bug?extid=55ad87f38795d6787521
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12e443d9e80000