linux-kernel - [PATCH AUTOSEL 4.14 15/19] ext4: Make sure quota files are not grabbed accidentally

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Message-Id: <20210910002309.176412-15-sashal@kernel.org>
Date:   Thu,  9 Sep 2021 20:23:05 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jan Kara <jack@...e.cz>, Theodore Ts'o <tytso@....edu>,
        Sasha Levin <sashal@...nel.org>, linux-ext4@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 15/19] ext4: Make sure quota files are not grabbed accidentally

From: Jan Kara <jack@...e.cz>

[ Upstream commit bd2c38cf1726ea913024393a0d11f2e2a3f4c180 ]

If ext4 filesystem is corrupted so that quota files are linked from
directory hirerarchy, bad things can happen. E.g. quota files can get
corrupted or deleted. Make sure we are not grabbing quota file inodes
when we expect normal inodes.

Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Link: https://lore.kernel.org/r/20210812133122.26360-1-jack@suse.cz
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ext4/inode.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9c07c8674b21..ca43540c2ced 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4719,6 +4719,7 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 	struct ext4_iloc iloc;
 	struct ext4_inode *raw_inode;
 	struct ext4_inode_info *ei;
+	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 	struct inode *inode;
 	journal_t *journal = EXT4_SB(sb)->s_journal;
 	long ret;
@@ -4729,9 +4730,12 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 	projid_t i_projid;
 
 	if ((!(flags & EXT4_IGET_SPECIAL) &&
-	     (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)) ||
+	     ((ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO) ||
+	      ino == le32_to_cpu(es->s_usr_quota_inum) ||
+	      ino == le32_to_cpu(es->s_grp_quota_inum) ||
+	      ino == le32_to_cpu(es->s_prj_quota_inum))) ||
 	    (ino < EXT4_ROOT_INO) ||
-	    (ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))) {
+	    (ino > le32_to_cpu(es->s_inodes_count))) {
 		if (flags & EXT4_IGET_HANDLE)
 			return ERR_PTR(-ESTALE);
 		__ext4_error(sb, function, line,
-- 
2.30.2