From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4243C3BE17F; Thu, 9 Apr 2026 14:37:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775745440; cv=none; b=A/nB4ovs1HbYKfO6AGajENd7ob+nEB/yBTkPtCiatvCIDOjIJpbdOwLlOFPIz9CmCuyUTkTEMQHkfyW+FwKSy5Mnxwlljk9UtDNWSH2VTveq28ij0aWMcUtMYni4kkg+4Q6vVyzqV4llbj2tzmmuY7amAHNo4la5W1XY26Xr5rQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775745440; c=relaxed/simple; bh=MJxNbTMCH0ezXiLcWQ+WBoX650y/sOmvOn2oJAqHK7k=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=u1er02Pa18u2W1+Gf8WMvzjAJRXpqmngKAgAeu/efl1xw2Vj+Wg0F/tDVUlnixVe7jsidDsHe2as8Qg2WFMTs+dCY7cFTvtY6kKELzotpmt67T4gHd5nI9r5FlrIL/qHk00SqigbJUga6XAhP5IRKMOTldaa2qIZasCCqEsxUuI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KjaGM6p2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="KjaGM6p2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE7EDC4CEF7; Thu, 9 Apr 2026 14:37:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775745440; bh=MJxNbTMCH0ezXiLcWQ+WBoX650y/sOmvOn2oJAqHK7k=; h=From:To:Cc:Subject:Date:From; b=KjaGM6p2l3vLLagFlCKKtt5GBEspXeCKUzZIRAL+idxDSya6xP7FMDVoR1bvfy5+0 t3C2nnZ3qYu9YkoyU7IVFfcVAnHfTVNOBY8Hztc3AuItgJBfwqkbCzoeIuHl6g4Nqg P0Y9FdMm/GD2ONVVrt5LbOkA35CIqYlQyjSsZaHA= From: Greg Kroah-Hartman To: ntfs3@lists.linux.dev Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Konstantin Komarov , stable Subject: [PATCH] fs/ntfs3: validate rec->used in journal-replay file record check Date: Thu, 9 Apr 2026 16:37:15 +0200 Message-ID: <2026040914-overbid-spherical-ac2e@gregkh> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2761; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=MJxNbTMCH0ezXiLcWQ+WBoX650y/sOmvOn2oJAqHK7k=; b=owGbwMvMwCRo6H6F97bub03G02pJDJnXd85uzkoL6Y3P2yG3zZJTOjkwfMt2CQ/mfVuqjvO8e 7GiVf1SRywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAEwkpp9hfumnb1td+kILA9NZ ltqYOy5OOdH8n2F+/JsLMdcdHx7fsmmPaNmCN0UM4acOAgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit check_file_record() validates rec->total against the record size but never validates rec->used. The do_action() journal-replay handlers read rec->used from disk and use it to compute memmove lengths: DeleteAttribute: memmove(attr, ..., used - asize - roff) CreateAttribute: memmove(..., attr, used - roff) change_attr_size: memmove(..., used - PtrOffset(rec, next)) When rec->used is smaller than the offset of a validated attribute, or larger than the record size, these subtractions can underflow allowing us to copy huge amounts of memory in to a 4kb buffer, generally considered a bad idea overall. This requires a corrupted filesystem, which isn't a threat model the kernel really needs to worry about, but checking for such an obvious out-of-bounds value is good to keep things robust, especially on journal replay Fix this up by bounding rec->used correctly. This is much like commit b2bc7c44ed17 ("fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot") which checked different values in this same switch statement. Cc: Konstantin Komarov Fixes: b46acd6a6a62 ("fs/ntfs3: Add NTFS journal") Cc: stable Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman --- fs/ntfs3/fslog.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c index 272e45276143..037df47fa9f3 100644 --- a/fs/ntfs3/fslog.c +++ b/fs/ntfs3/fslog.c @@ -2791,13 +2791,14 @@ static inline bool check_file_record(const struct MFT_REC *rec, u16 fn = le16_to_cpu(rec->rhdr.fix_num); u16 ao = le16_to_cpu(rec->attr_off); u32 rs = sbi->record_size; + u32 used = le32_to_cpu(rec->used); /* Check the file record header for consistency. */ if (rec->rhdr.sign != NTFS_FILE_SIGNATURE || fo > (SECTOR_SIZE - ((rs >> SECTOR_SHIFT) + 1) * sizeof(short)) || (fn - 1) * SECTOR_SIZE != rs || ao < MFTRECORD_FIXUP_OFFSET_1 || ao > sbi->record_size - SIZEOF_RESIDENT || !is_rec_inuse(rec) || - le32_to_cpu(rec->total) != rs) { + le32_to_cpu(rec->total) != rs || used > rs || used < ao) { return false; } @@ -2809,6 +2810,15 @@ static inline bool check_file_record(const struct MFT_REC *rec, return false; } + /* + * The do_action() handlers compute memmove lengths as + * "rec->used - ", which underflows when + * rec->used is smaller than the attribute walk reached. At this + * point attr is the ATTR_END marker; rec->used must cover it. + */ + if (used < PtrOffset(rec, attr) + sizeof(attr->type)) + return false; + return true; } -- 2.53.0