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ntfs3: fix uninit memory after failed mi_read in mi_format_new 

Fix a KMSAN un-init bug found by syzkaller.

ntfs_get_bh() expects a buffer from sb_getblk(), that buffer may not be
uptodate. We do not bring the buffer uptodate before setting it as
uptodate. If the buffer were to not be uptodate, it could mean adding a
buffer with un-init data to the mi record. Attempting to load that record
will trigger KMSAN.

Avoid this by setting the buffer as uptodate, if it’s not already, by
overwriting it.

Reported-by: syzbot+7a2ba6b7b66340cff225@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7a2ba6b7b66340cff225
Tested-by: syzbot+7a2ba6b7b66340cff225@syzkaller.appspotmail.com
Fixes: 4342306f0f ("fs/ntfs3: Add file operations and implementation")
Signed-off-by: Raphael Pinsonneault-Thibeault <rpthibeault@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
This commit is contained in:
Raphael Pinsonneault-Thibeault 2025-10-12 16:16:34 -04:00 committed by Konstantin Komarov
parent 02f312754c
commit 73e6b9dacf
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1 changed files with 8 additions and 1 deletions
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7
fs/ntfs3/fsntfs.c
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@ -1349,7 +1349,14 @@ int ntfs_get_bh(struct ntfs_sb_info *sbi, const struct runs_tree *run, u64 vbo,
}
if (buffer_locked(bh))
__wait_on_buffer(bh);
lock_buffer(bh);
if (!buffer_uptodate(bh))
{
memset(bh->b_data, 0, blocksize);
set_buffer_uptodate(bh);
}
unlock_buffer(bh);
} else {
bh = ntfs_bread(sb, block);
if (!bh) {