From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 83C9247252B; Tue, 21 Jul 2026 20:23:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665420; cv=none; b=NywNfy0YQVrqC4vM2UNJ4g/u4JynnMRjCGtRAT9mv+mNxD523pKoU6jfLtAmPk4xUg1rCpiwHwYBclsjtjzzc4yibprcxrT5eLjuY6KDMzwqUwya1bleiJmPI2CsyUnmLQGStSfoB88z2GbdLwwURZ2fksaEuvHcb2TYAkHDSt4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665420; c=relaxed/simple; bh=YbT1DIt3/M2+/Xs4DNbNCanw9wC+GxzMWR0tN05nvnI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eHVrnqqtnLyPaLQvSU0mZ4NYuhAZBI172+xuZQrqqSloL86Y0uCioc12unWPfoqc2I8NZ5XmCa+dhg8tLvd/KAuK1jaa7eCsIUAvwmHMoZ1bS4VHpbJ2X2Y6ZIJZLiSMCSmMObDgJmTnFIf5pKlsqHpdESuywOdHBnVLjPYjPag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=qCu34kcM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="qCu34kcM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E99BF1F000E9; Tue, 21 Jul 2026 20:23:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784665419; bh=8gZ9/QX+h+hxSckT3hWFcydGVF7Bk47aH9yLtZcclQI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=qCu34kcMVEXWCx4myZBhERziGhqfAiWgtux1jalIHlIU7bcJU25cND4L+BN7YPXC9 0OVZ9+/SORISqkAWj9aszfbw/6J03p6fqNGFVYVn2HaazWlPiKHVtcRYvcifzvEUiQ wxjyl3HzD0xmxHC+OxW63EH74/xdY41gpUNzVCD8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Namjae Jeon , Bryam Vargas Subject: [PATCH 6.6 0297/1266] exfat: bound uniname advance in exfat_find_dir_entry() Date: Tue, 21 Jul 2026 17:12:14 +0200 Message-ID: <20260721152448.472150580@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bryam Vargas commit 3a1230e7b043c62737b05a3e9275ca83a43ad20a upstream. In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the output pointer by a fixed amount while the loop guard only tracks the accumulated name length: if (++order == 2) uniname = p_uniname->name; else uniname += EXFAT_FILE_NAME_LEN; len = exfat_extract_uni_name(ep, entry_uniname); name_len += len; unichar = *(uniname+len); *(uniname+len) = 0x0; uniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len grows only by the actual extracted length, which is shorter when a name fragment contains an early NUL. The only guard is `name_len >= MAX_NAME_LENGTH`, so a crafted directory with many short name fragments lets uniname run far past the p_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small, causing an out-of-bounds read and write at *(uniname+len). The sibling extractor exfat_get_uniname_from_ext_entry() already stops on a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard added in commit d42334578eba ("exfat: check if filename entries exceeds max filename length")); exfat_find_dir_entry() never got the equivalent. Track the per-entry write offset as a count and reject a fragment once the offset, or the offset plus the extracted length, would exceed MAX_NAME_LENGTH, before forming the output pointer. Fixes: ca06197382bd ("exfat: add directory operations") Cc: stable@vger.kernel.org Suggested-by: Namjae Jeon Signed-off-by: Bryam Vargas Signed-off-by: Namjae Jeon Signed-off-by: Greg Kroah-Hartman --- fs/exfat/dir.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/fs/exfat/dir.c +++ b/fs/exfat/dir.c @@ -1081,6 +1081,7 @@ rewind: if (entry_type == TYPE_EXTEND) { unsigned short entry_uniname[16], unichar; + unsigned int offset; if (step != DIRENT_STEP_NAME || name_len >= MAX_NAME_LENGTH) { @@ -1089,13 +1090,15 @@ rewind: continue; } - if (++order == 2) - uniname = p_uniname->name; - else - uniname += EXFAT_FILE_NAME_LEN; - + offset = (++order - 2) * EXFAT_FILE_NAME_LEN; len = exfat_extract_uni_name(ep, entry_uniname); brelse(bh); + if (offset > MAX_NAME_LENGTH || + len > MAX_NAME_LENGTH - offset) { + step = DIRENT_STEP_FILE; + continue; + } + uniname = p_uniname->name + offset; name_len += len; unichar = *(uniname+len);