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exfat: fix the new buffer was not zeroed before writing

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Before writing, if a buffer_head marked as new, its data must
be zeroed, otherwise uninitialized data in the page cache will
be written.

So this commit uses folio_zero_new_buffers() to zero the new
buffers before ->write_end().

Fixes: 6630ea4910 ("exfat: move extend valid_size into ->page_mkwrite()")
Reported-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=91ae49e1c1a2634d20c0
Tested-by: syzbot+91ae49e1c1a2634d20c0@syzkaller.appspotmail.com
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Yuezhang Mo 2024-12-12 16:29:23 +08:00 committed by Namjae Jeon
parent fee873761b
commit 98e2fb26d1
1 changed files with 6 additions and 0 deletions
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6
fs/exfat/file.c
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@ -545,6 +545,7 @@ static int exfat_extend_valid_size(struct file *file, loff_t new_valid_size)
while (pos < new_valid_size) {
u32 len;
struct folio *folio;
unsigned long off;
len = PAGE_SIZE - (pos & (PAGE_SIZE - 1));
if (pos + len > new_valid_size)
@ -554,6 +555,9 @@ static int exfat_extend_valid_size(struct file *file, loff_t new_valid_size)
if (err)
goto out;
off = offset_in_folio(folio, pos);
folio_zero_new_buffers(folio, off, off + len);
err = ops->write_end(file, mapping, pos, len, len, folio, NULL);
if (err < 0)
goto out;
@ -563,6 +567,8 @@ static int exfat_extend_valid_size(struct file *file, loff_t new_valid_size)
cond_resched();
}
return 0;
out:
return err;
}