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 BDD6549B5A9 for ; Tue, 22 Sep 2026 19:55:05 +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=1790106908; cv=none; b=csGKDkaqKlV51NpRFoBYnolPo45zmO5RKG9OPQfGS2Y5b7bivijL+yKU8ufBxzPad1fLS7umU9BZ/l4ehgaQ1aYA2ofL3gAktHsWj+K/FEe95H1oUwLIBBv++eYmu/PUKCg4RdUiNBz5yvAYwBoMpmfZpC9vaUOsJtIoKuP4Pto= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790106908; c=relaxed/simple; bh=r0NXGua0iVhsSCyg/y0NynaR5qBc6TtmI608czlHxbw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KBSCNAmuLXE3blYbx2WL7vZoldYvDOB85iiZeaKBmDW1hl5sCIUzLDMw4uWDxjEGp117f1SSNfQTogp6DIZOjU/Nc6o4rW64CqCjp7+AZwRdElLXOyUhyA/i7s8HNIqk5wXUIHujO7nbotOVa8xWY+M/FMznLOOptJ6JYAuUg3g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G5GCSEAg; 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="G5GCSEAg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DAF91F000FF; Tue, 22 Sep 2026 19:55:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790106904; bh=YZaCJBkWUrj7SPQcKkj/sNp7NZaX3IthhtYvYH2Mskc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=G5GCSEAg0A/b+TUU9mg8j0YMTL3SMP+WOLF5Z9enw6nrWwWLzgg1p0hF+d9FNcnC1 WtdvvWFb00zaZ38yzUSsYliEJHdCONK05p8wn4qS3QCccAtMXna7UYWmbc6PdlnHP8 ZF8zV16AB9MKkns7vLQgEGmsM5jp/APpVrhAHZYdtZSCC8HteqGFoglMrbAvcIMFOU rX64anP9nhTg/mJNLDzDOJR7tCHBNWpp60y0xaKhD/ncHKMOPHAcjtNx6mom4mdUvN kl9mx00vt+rJcPWbRFCy3nWDNTYRXk3KOqGrh5/utGAZeyr2OZjVu2G4lPkyjlUduJ u7F2SFG8w8F2A== From: Sasha Levin To: stable@vger.kernel.org Cc: Frank Sorenson , David Howells , Paulo Alcantara , Sasha Levin Subject: [PATCH 5.15.y] smb: client: fix potential OOB read in smb3_enum_snapshots() Date: Tue, 22 Sep 2026 15:55:01 -0400 Message-ID: <20260922195501.134716-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026092245-kick-debug-cfb1@gregkh> References: <2026092245-kick-debug-cfb1@gregkh> 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 4775c3b7a597907e0b97556c7986fda238a377ae ] If snapshot_array_size is smaller than GMT_TOKEN_SIZE, smb3_enum_snapshots() sets ret_data_len to sizeof(struct smb_snapshot_array) without verifying the actual length of the server's reply. Because SMB2_ioctl() places no lower bound on the server-supplied OutputCount and allocates retbuf to exactly that length, a short reply results in ret_data_len exceeding the size of retbuf. The subsequent copy_to_user() then reads past the end of retbuf, leaking adjacent slab memory to userspace. The subsequent clamp check is ineffective as it only reduces ret_data_len. Fix this by rejecting replies shorter than sizeof(struct smb_snapshot_array) with -EIO. Note that the bound is set to the 12-byte struct size rather than the 16-byte MIN_SNAPSHOT_ARRAY_SIZE defined in MS-SMB2 3.3.5.15.1, because 12 bytes is exactly what copy_to_user() attempts to read. Fixes: e02789a53d71 ("smb3: enumerating snapshots was leaving part of the data off end") Cc: stable@vger.kernel.org Signed-off-by: Frank Sorenson Reviewed-by: David Howells Signed-off-by: Paulo Alcantara Signed-off-by: Sasha Levin --- fs/cifs/smb2ops.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 3aaa45375d8ba..42b5e5264fb6e 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2271,8 +2271,14 @@ smb3_enum_snapshots(const unsigned int xid, struct cifs_tcon *tcon, * and retry the ioctl again with larger array size sufficient * to hold all of the snapshot GMT tokens on the second try. */ - if (snapshot_in.snapshot_array_size < GMT_TOKEN_SIZE) + if (snapshot_in.snapshot_array_size < GMT_TOKEN_SIZE) { + if (ret_data_len < sizeof(struct smb_snapshot_array)) { + rc = -EIO; + kfree(retbuf); + return rc; + } ret_data_len = sizeof(struct smb_snapshot_array); + } /* * We return struct SRV_SNAPSHOT_ARRAY, followed by -- 2.53.0