linux-kernel - [PATCH] ext4: fix error code return to user-space in ext4_get

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Date:   Wed,  9 Nov 2022 18:14:45 +0000
From:   Luís Henriques <lhenriques@...e.de>
To:     "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        Luís Henriques <lhenriques@...e.de>
Subject: [PATCH] ext4: fix error code return to user-space in ext4_get_branch()

If a block is out of range in ext4_get_branch(), -ENOMEM will be returned
to user-space.  Obviously, this error code isn't really useful.  This
patch fixes it by making sure the right error code (-EFSCORRUPTED) is
propagated to user-space.  EUCLEAN is more informative than ENOMEM.

Signed-off-by: Luís Henriques <lhenriques@...e.de>
---
Hi Ted!

Just a note: this patch, as you suggested, is taken from the patch with
message-id 20221011155623.14840-1-lhenriques@...e.de .

Cheers,
--
Luís

 fs/ext4/indirect.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 860fc5119009..c68bebe7ff4b 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -148,6 +148,7 @@ static Indirect *ext4_get_branch(struct inode *inode, int depth,
 	struct super_block *sb = inode->i_sb;
 	Indirect *p = chain;
 	struct buffer_head *bh;
+	unsigned int key;
 	int ret = -EIO;
 
 	*err = 0;
@@ -156,7 +157,13 @@ static Indirect *ext4_get_branch(struct inode *inode, int depth,
 	if (!p->key)
 		goto no_block;
 	while (--depth) {
-		bh = sb_getblk(sb, le32_to_cpu(p->key));
+		key = le32_to_cpu(p->key);
+		if (key > ext4_blocks_count(EXT4_SB(sb)->s_es)) {
+			/* the block was out of range */
+			ret = -EFSCORRUPTED;
+			goto failure;
+		}
+		bh = sb_getblk(sb, key);
 		if (unlikely(!bh)) {
 			ret = -ENOMEM;
 			goto failure;