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 1ABB344AB91; Tue, 21 Jul 2026 22:36:13 +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=1784673374; cv=none; b=t5vMIrl56jRVDrOJAeDOBhu8jgvEAFFhA3X4bAMU2hrbbvbOjdY/TjLnbqfEEATWWelpy2E6YOlOhuWg4BdjI/GAKfPWJ8ivfal5pZRY1jKkc95xxrCn6UgklsYPIO4LR3jORQ4anPgeOLX/dY2uG4RtHqLMn8l+I4FA1ohCB2o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784673374; c=relaxed/simple; bh=Y4NLaC/+IrBZIotZdIRB602hrWho0W+D1ntyeSej6i4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=awm/qsypYxiKxfn60Jc9Fjb4ru7s4Z4eWyH3hKvI3Uh19oCPoEHxB+JZV4h7vWg9Tbo5W5ke45MXZlx8+0dQy/hqRA26GnAiYmuQ+KGzlRCAD97YTOGVW3loq/76iazvZL7FDptMzYv+WUAYcH4YAGjNrs0TVBVJpbWcBbolMtE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=U4qS446Q; 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="U4qS446Q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 804CF1F00A3A; Tue, 21 Jul 2026 22:36:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784673373; bh=2XwkPwn7N0wDgSfhUKgzdDdrSAjrUNmoLRdpD6Wdw7M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=U4qS446Qb6re7XDq4vPBJjLz16K7YCkr17QMH+FHwgl6JKHJFJUtY5gV4lIroIOOF 0QBYfw+c0L3vHf5edMRpND3kwK/LlKf4FlOQ7yvsWbQwPAHJY5+jGJxCfqhipou22b mOcAvrKYW46JuHpT5sPpSqwd+2iYachmcH1N5f+8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Namjae Jeon , Bryam Vargas Subject: [PATCH 5.10 139/699] exfat: bound uniname advance in exfat_find_dir_entry() Date: Tue, 21 Jul 2026 17:18:18 +0200 Message-ID: <20260721152358.844446200@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152355.667394603@linuxfoundation.org> References: <20260721152355.667394603@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 5.10-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 @@ -1045,6 +1045,7 @@ 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) { @@ -1053,13 +1054,15 @@ 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);