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erofs: fix order >= MAX_ORDER warning due to crafted negative i_size

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[ Upstream commit 1dd73601a1cba37a0ed5f89a8662c90191df5873 ]

As syzbot reported [1], the root cause is that i_size field is a
signed type, and negative i_size is also less than EROFS_BLKSIZ.
As a consequence, it's handled as fast symlink unexpectedly.

Let's fall back to the generic path to deal with such unusual i_size.

[1] https://lore.kernel.org/r/000000000000ac8efa05e7feaa1f@google.com

Reported-by: syzbot+f966c13b1b4fc0403b19@syzkaller.appspotmail.com
Fixes: 431339ba9042 ("staging: erofs: add inode operations")
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20220909023948.28925-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Gao Xiang 2022-09-09 10:39:48 +08:00 committed by Greg Kroah-Hartman
parent ca9f27448a
commit acc2f40b98
1 changed files with 1 additions and 1 deletions
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2
fs/erofs/inode.c
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@ -222,7 +222,7 @@ static int erofs_fill_symlink(struct inode *inode, void *data,
/* if it cannot be handled with fast symlink scheme */
if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
inode->i_size >= PAGE_SIZE) {
inode->i_size >= PAGE_SIZE || inode->i_size < 0) {
inode->i_op = &erofs_symlink_iops;
return 0;
}