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 887FD35DA6E for ; Wed, 23 Sep 2026 01:40:22 +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=1790127623; cv=none; b=DIV/HdhD3Roaebg+zzaDQkf3FXhTDgPleshS6N4h/j8d17KXm9i8jkGlQQFHELVTLZcuq8AKPrxeutuQgOAEplbbLVIbb1ACv+W5dZoVB+Vog00afl088dkO2r34lsZXDAC2f2kkOOmzjPBFAWVWZenHMJ2SXoiH1X7PK3lVSLo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790127623; c=relaxed/simple; bh=VW1Hiwp2ILKHWnJEmqpnNyO/disSdziOQKQ43tEoiwU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=o0u1nWee689z4nstmvZrDOEDBvGngEefYdri63pNfXd9a3EDdYAAyCEkkFWbG9WYghbznOtI7iStmAX+zoUndicMfIPb5q4/UpeqU+mIi/tBu5nUJzkrfGFDN4L22GyrpGzB8QghPQMTrK1vnA9qwNPHHHlci2F/9ofxXH0QRec= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LbRiAn13; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LbRiAn13" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC9231F00898; Wed, 23 Sep 2026 01:40:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790127622; bh=83zIyWJUxHzATQIzUHRMSVie/cH0tnz3rHwLlpsjd5U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LbRiAn131aOxKKbIqz5w5MnRgAKAKeruzQ3R/CERQ7Nvz+X83Mod/oz3d7pRoV/Qs Ls0NtEmLMkd0vyHBXAMI/FlhFVKgVK0AK2U/PfxbQ/Y+EsewQX8cYRwt72vTWqkAZJ BpuVOZT78Cj8hFTMq1/KyYR1wrJxCgOGY3393xU2v/sZFrqRF/KUi6Jn3GqFLCI9b+ oSj6HfakOMZgYjOJE8xvHt4AeW3ZFLOqchqNkrDx3RtRmhxD3cbIpB57Bfsvz8RRaA sJ4imhi7rX8PfQcPaig4UfWU1HKM4d7m1Ym4T935OdhClJVlO+CpfxIvkS4ZVIq54n ig8P9GjR9nCkA== From: Sasha Levin To: stable@vger.kernel.org Cc: Frank Sorenson , David Howells , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.15.y 2/2] smb: client: fix missing lower-bound check on DFS referral string offsets Date: Tue, 22 Sep 2026 21:40:19 -0400 Message-ID: <20260923014019.880289-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260923014019.880289-1-sashal@kernel.org> References: <2026092229-hypertext-grunge-945c@gregkh> <20260923014019.880289-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Frank Sorenson [ Upstream commit e83330c55edc0c3ac08aa6c95e49e4694c65523b ] parse_dfs_referrals() checks that DfsPathOffset and NetworkAddressOffset do not exceed the buffer end, but fails to check that they don't point inside the referral header itself. If a server provides an offset smaller than sizeof(struct dfs_referral_level_3), the derived string pointer overlaps with the struct fields, causing cifs_strndup_from_utf16() to interpret header data as UTF-16 strings. Fix this by enforcing that string offsets are at least sizeof(*ref). Fixes: 4ecce920e13a ("CIFS: move DFS response parsing out of SMB1 code") Cc: stable@vger.kernel.org Signed-off-by: Frank Sorenson Reviewed-by: David Howells Signed-off-by: Paulo Alcantara [ Redirected the patch from fs/smb/client/misc.c to fs/cifs/misc.c. ] Signed-off-by: Sasha Levin --- fs/cifs/misc.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 729624ae9d876..a477bffdd3e80 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -920,7 +920,11 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size, node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags); /* copy DfsPath */ - if (le16_to_cpu(ref->DfsPathOffset) > data_end - (char *)ref) { + if (le16_to_cpu(ref->DfsPathOffset) < sizeof(*ref) || + le16_to_cpu(ref->DfsPathOffset) > data_end - (char *)ref) { + cifs_dbg(VFS, "%s: DfsPathOffset %u out of range [%zu, %td]\n", + __func__, le16_to_cpu(ref->DfsPathOffset), + sizeof(*ref), data_end - (char *)ref); rc = -EINVAL; goto parse_DFS_referrals_exit; } @@ -934,7 +938,11 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size, } /* copy link target UNC */ - if (le16_to_cpu(ref->NetworkAddressOffset) > data_end - (char *)ref) { + if (le16_to_cpu(ref->NetworkAddressOffset) < sizeof(*ref) || + le16_to_cpu(ref->NetworkAddressOffset) > data_end - (char *)ref) { + cifs_dbg(VFS, "%s: NetworkAddressOffset %u out of range [%zu, %td]\n", + __func__, le16_to_cpu(ref->NetworkAddressOffset), + sizeof(*ref), data_end - (char *)ref); rc = -EINVAL; goto parse_DFS_referrals_exit; } -- 2.53.0