From: Lizhi Xu <lizhi.xu@windriver.com>
Date: Thu, 8 Jan 2026 15:04:27 +0000 (-0300)
Subject: ext4: filesystems without casefold feature cannot be mounted with siphash
X-Git-Tag: v5.15.198~63
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=86b81d4eab1cd4c56f7447896232cf33472c2395;p=thirdparty%2Fkernel%2Fstable.git

ext4: filesystems without casefold feature cannot be mounted with siphash

commit 985b67cd86392310d9e9326de941c22fc9340eec upstream.

When mounting the ext4 filesystem, if the default hash version is set to
DX_HASH_SIPHASH but the casefold feature is not set, exit the mounting.

Reported-by: syzbot+340581ba9dceb7e06fb3@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
Link: https://patch.msgid.link/20240605012335.44086-1-lizhi.xu@windriver.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[cascardo: small conflict fixup]
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/super.c b/fs/ext4/super.c
index 65fd42a2105df..9a061c7503054 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3191,6 +3191,14 @@ 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;