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ext4: fix error message when rejecting the default hash

PATCH New Ankan Biswas 1 participant 1 message Dec 15, 2025 Stable branch

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PATCH 1/1 ext4: fix error message when rejecting the default hash

From: Gabriel Krisman Bertazi <[email protected]>

[ Upstream commit a2187431c395cdfbf144e3536f25468c64fc7cfa ]

Commit 985b67cd8639 ("ext4: filesystems without casefold feature cannot be mounted with siphash") properly rejects volumes where s_def_hash_version is set to DX_HASH_SIPHASH, but the check and the error message should not look into casefold setup - a filesystem should never have DX_HASH_SIPHASH as the default hash. Fix it and, since we are there, move the check to ext4_hash_info_init.

Fixes 985b67cd8639 ("ext4: filesystems without casefold feature cannot

be mounted with siphash")

Signed-off-by Gabriel Krisman Bertazi <[email protected]>
Link https://patch.msgid.link/[email protected] open here
Signed-off-by Theodore Ts'o <[email protected]>

[ The commit a2187431c395 intended to remove the if-block which was used
for an old SIPHASH rejection check. ]

Signed-off-by Ankan Biswas <[email protected]>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/super.c | 20 +++++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)
fs/ext4/ext4.h +1 -0
index 7afce7b744c0..85ba12a48f26 100644
@@ -2459,6 +2459,7 @@ static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)
 #define DX_HASH_HALF_MD4_UNSIGNED	4
 #define DX_HASH_TEA_UNSIGNED		5
 #define DX_HASH_SIPHASH			6
+#define DX_HASH_LAST 			DX_HASH_SIPHASH
 
 static inline u32 ext4_chksum(struct ext4_sb_info *sbi, u32 crc,
 			      const void *address, unsigned int length)
fs/ext4/super.c +17 -3
index 16a6c249580e..613f2bac439d 100644
@@ -5138,16 +5138,27 @@ static int ext4_load_super(struct super_block *sb, ext4_fsblk_t *lsb,
 	return ret;
 }
 
-static void ext4_hash_info_init(struct super_block *sb)
+static int ext4_hash_info_init(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_super_block *es = sbi->s_es;
 	unsigned int i;
 
+	sbi->s_def_hash_version = es->s_def_hash_version;
+
+	if (sbi->s_def_hash_version > DX_HASH_LAST) {
+		ext4_msg(sb, KERN_ERR,
+			 "Invalid default hash set in the superblock");
+		return -EINVAL;
+	} else if (sbi->s_def_hash_version == DX_HASH_SIPHASH) {
+		ext4_msg(sb, KERN_ERR,
+			 "SIPHASH is not a valid default hash value");
+		return -EINVAL;
+	}
+
 	for (i = 0; i < 4; i++)
 		sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
 
-	sbi->s_def_hash_version = es->s_def_hash_version;
 	if (ext4_has_feature_dir_index(sb)) {
 		i = le32_to_cpu(es->s_flags);
 		if (i & EXT2_FLAGS_UNSIGNED_HASH)

@@ -5165,6 +5176,7 @@ static void ext4_hash_info_init(struct super_block *sb)
 #endif
 		}
 	}
+	return 0;
 }
 
 static int ext4_block_group_meta_init(struct super_block *sb, int silent)

@@ -5309,7 +5321,9 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	if (err)
 		goto failed_mount;
 
-	ext4_hash_info_init(sb);
+	err = ext4_hash_info_init(sb);
+	if (err)
+		goto failed_mount;
 
 	err = ext4_handle_clustersize(sb);
 	if (err)
Signature · 1 line
2.52.0