6.12-stable review patch. If anyone has any objections, please let me know.
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From: Yuezhang Mo Yuezhang.Mo@sony.com
[ Upstream commit 98e2fb26d1a9eafe79f46d15d54e68e014d81d8c ]
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: 6630ea49103c ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/exfat/file.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/exfat/file.c b/fs/exfat/file.c index fb38769c3e39..05b51e721783 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -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; }