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 8876C359F98; Fri, 9 Jan 2026 12:00:27 +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=1767960027; cv=none; b=S2RtxJTeTPLX6LMjfgWpwSzrP6hMlumpExkpXox0dvWeLMNbephr91pqrzKkCVWE4InTiOSavKQz1+dnkxvOCjKw1pclJ19TdmtzsrGv/mlKZzqx5BwdUlWRttTOFdKU17c6DhLjGqNh6dgq2OJ1fU8ns04KUHl4Cce0rlNPS1U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767960027; c=relaxed/simple; bh=g1yY980xtbVP4PNP02hxw9IBxmI6WjLQkDepYsELr0w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=MGVkO7o/Dc+UJ0vUWtUDYxJNd1cFwOEN3h/H/ocy6rOHOk49UztR8UkXv8RDouIuXmwFUPqlB6SIMr26ZveQFfIFdcNZtLx9Ue1ZOKRFO/AataVXE7mYhR41eFDbHeazA6gBKEaqIiC/uu2f1S4egDMpVNTILMqwBslnROLE5tw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZdHckdUj; 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="ZdHckdUj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18D72C4CEF1; Fri, 9 Jan 2026 12:00:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767960027; bh=g1yY980xtbVP4PNP02hxw9IBxmI6WjLQkDepYsELr0w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZdHckdUjLC3vi56FKdcOREeyFUZJDY67zmai6eQqXBNuwTfxkA4ZI7M45cuLNR618 g9yo0MtQ839cGb5vvFEmRJZvCauCppWR7ogpTdygRyJIi9TgwsOPWswRwl4G4Klri1 BBoj2NtxE30t+kYKuNR20frMf1WYSyNArgCMayWQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Armin Wolf , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Sasha Levin Subject: [PATCH 6.6 260/737] fs/nls: Fix utf16 to utf8 conversion Date: Fri, 9 Jan 2026 12:36:39 +0100 Message-ID: <20260109112143.772034324@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260109112133.973195406@linuxfoundation.org> References: <20260109112133.973195406@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Armin Wolf [ Upstream commit 25524b6190295577e4918c689644451365e6466d ] Currently the function responsible for converting between utf16 and utf8 strings will ignore any characters that cannot be converted. This however also includes multi-byte characters that do not fit into the provided string buffer. This can cause problems if such a multi-byte character is followed by a single-byte character. In such a case the multi-byte character might be ignored when the provided string buffer is too small, but the single-byte character might fit and is thus still copied into the resulting string. Fix this by stop filling the provided string buffer once a character does not fit. In order to be able to do this extend utf32_to_utf8() to return useful errno codes instead of -1. Fixes: 74675a58507e ("NLS: update handling of Unicode") Signed-off-by: Armin Wolf Link: https://patch.msgid.link/20251111131125.3379-2-W_Armin@gmx.de Reviewed-by: Ilpo Järvinen Signed-off-by: Ilpo Järvinen Signed-off-by: Sasha Levin --- fs/nls/nls_base.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/nls/nls_base.c b/fs/nls/nls_base.c index a026dbd3593f6..7eacded3c17d1 100644 --- a/fs/nls/nls_base.c +++ b/fs/nls/nls_base.c @@ -94,7 +94,7 @@ int utf32_to_utf8(unicode_t u, u8 *s, int maxout) l = u; if (l > UNICODE_MAX || (l & SURROGATE_MASK) == SURROGATE_PAIR) - return -1; + return -EILSEQ; nc = 0; for (t = utf8_table; t->cmask && maxout; t++, maxout--) { @@ -110,7 +110,7 @@ int utf32_to_utf8(unicode_t u, u8 *s, int maxout) return nc; } } - return -1; + return -EOVERFLOW; } EXPORT_SYMBOL(utf32_to_utf8); @@ -217,8 +217,16 @@ int utf16s_to_utf8s(const wchar_t *pwcs, int inlen, enum utf16_endian endian, inlen--; } size = utf32_to_utf8(u, op, maxout); - if (size == -1) { - /* Ignore character and move on */ + if (size < 0) { + if (size == -EILSEQ) { + /* Ignore character and move on */ + continue; + } + /* + * Stop filling the buffer with data once a character + * does not fit anymore. + */ + break; } else { op += size; maxout -= size; -- 2.51.0