From: Gabriel Krisman Bertazi <krisman@suse.de>
Date: Thu, 8 Jan 2026 15:04:09 +0000 (-0300)
Subject: ext4: fix error message when rejecting the default hash
X-Git-Tag: v6.1.160~14
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d4da9edac3385ba7454edab0b8e182efed0c65ad;p=thirdparty%2Fkernel%2Fstable.git

ext4: fix error message when rejecting the default hash

commit a2187431c395cdfbf144e3536f25468c64fc7cfa upstream.

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 <krisman@suse.de>
Link: https://patch.msgid.link/87jzg1en6j.fsf_-_@mailhost.krisman.be
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 579c4ac511ec7..27753291fb7ec 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2460,6 +2460,7 @@ 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)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 91d9873df8d45..fa5642838c79c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3552,14 +3552,6 @@ int ext4_feature_set_ok(struct super_block *sb, int readonly)
 	}
 #endif
 
-	if (EXT4_SB(sb)->s_es->s_def_hash_version == DX_HASH_SIPHASH &&
-	    !ext4_has_feature_casefold(sb)) {
-		ext4_msg(sb, KERN_ERR,
-			 "Filesystem without casefold feature cannot be "
-			 "mounted with siphash");
-		return 0;
-	}
-
 	if (readonly)
 		return 1;
 
@@ -5043,16 +5035,27 @@ out:
 	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)
@@ -5070,6 +5073,7 @@ static void ext4_hash_info_init(struct super_block *sb)
 #endif
 		}
 	}
+	return 0;
 }
 
 static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
@@ -5224,7 +5228,9 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	sbi->s_addr_per_block_bits = ilog2(EXT4_ADDR_PER_BLOCK(sb));
 	sbi->s_desc_per_block_bits = ilog2(EXT4_DESC_PER_BLOCK(sb));
 
-	ext4_hash_info_init(sb);
+	err = ext4_hash_info_init(sb);
+	if (err)
+		goto failed_mount;
 
 	if (ext4_handle_clustersize(sb))
 		goto failed_mount;