From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793831539; b=z3quvckeYbKAjmU36IrZPjFjamRDjw0fy/5b0pM1WYf6PtXPYgbGbd5PtgmtiN9BS37s +4wPtE/+5YeFHWOCCKUWhYmr4/aVt+kRa0btgfXQuaXCLTs52ZaJe78P5oABpjL0P3Uf5 oojzMkaNGB0GKa/nA1jXIXZMQqfJ3z+NCNEBLMHbA3Iv57zgvBkSsr24UeOPtyD7eFK2U WgkY9dz5hQ1cZJlojvWE4lYWSUC04vmuLgo+67WKVlOH1cXt8W3MGlPgHOtR+wi3FM9mc XiE4ZfE342bG+qpP0WvUL5e1ss/urywfoPl2oGw7612vFWY9rmrtDcKsyfTFLSOQWrg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831539; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=rerrs5uyAerDdgcHpwU0EvyJuR+Bjg5mBmA2axKB9xo=; b=CKepzGS5mReSDF5FECpcrTT29YQEQBHi/egR6QX8MnFirfMQv6sJ6JRfjeuND3GAuKo8 cPCYquv+Uu82jWAwGk5ciwwyZdRfnie3bugRNexyrAwLwjF291HK8/XOW0stDpxPOkce+ fv0HInAA14BBaVgMrTwuLYRbtEYjrak4ZEC9L3p5efqZOZZmWwdbYojQXE+F4agRJe4zE RPYuhssc4z0uJeAlEV9LdEdBcJyAcu7aY86IyJH+L2J/WUkoPFW87/G72WCTT2uI1F07p pIHV6kAvVknsVZf2+FeHQMzGW5lR6EF1SYxSRm+06KnybI+ETn0KUpVfPS9dv09aVWw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=z1BhZNEN; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B6A58606A332; Wed, 4 Nov 2026 22:32:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=z1BhZNEN Received: by smtp.kernel.org (Postfix) with ESMTPSA id 489181F000C1; Wed, 4 Nov 2026 22:32:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831538; bh=rerrs5uyAerDdgcHpwU0EvyJuR+Bjg5mBmA2axKB9xo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=z1BhZNENbeN7QnoWJ1xEmbVi958XSPLP/F8gSHCpBsMI+KJumryh1C6HJErmOWn/0 6d0JfQ1bEKwvYbGw6GX/MQN0VAzYEky0sS1Fk+B4nRQJkMjDQqQRovrg1nOtFO2FVz LU+P73yeo1UnC9f7DdpgppuRPiJpTOEqZlPH49iQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fahad Alharbi , Chris Mason , Josef Bacik , Amir Goldstein Subject: [PATCH 6.18 0766/1005] ovl: do not copy up an xattr value that was never read Date: Wed, 4 Nov 2026 16:08:19 -0500 Message-ID: <20261104211104.863755193@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Mason commit 755b5c5c9277be251a51623d6065abab948c61bc upstream. Copy-up stores uninitialized kernel memory in an xattr of the upper file, where the user can read it. ovl_copy_xattr() may only pass bytes to ovl_do_setxattr() that ovl_do_getxattr() has read. When the read fails with -ERANGE the function asks for the size again, and if the new size fits the buffer it stores the buffer although nothing was read into it. The buffer comes from kvmalloc(), or it still holds the value of the previous xattr. A FUSE lower layer that answers every sized GETXATTR with -ERANGE made copy-up store 4096 bytes that the server never sent, with a kernel pointer in them, as an xattr of the upper file. Fix this by failing the copy-up with -EIO when the size that follows -ERANGE fits the buffer. Reported-by: Fahad Alharbi Closes: https://lore.kernel.org/linux-fsdevel/CAOQ4uxjhfpNVvoVrTayj46H2CViTOc3oxzM6xdb8+E7ikE2CSA@mail.gmail.com/ Fixes: e4ad29fa0d22 ("ovl: use a minimal buffer in ovl_copy_xattr") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason Signed-off-by: Josef Bacik Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/copy_up.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -131,8 +131,12 @@ int ovl_copy_xattr(struct super_block *s retry: size = ovl_do_getxattr(oldpath, name, value, value_size); - if (size == -ERANGE) + if (size == -ERANGE) { size = ovl_do_getxattr(oldpath, name, NULL, 0); + /* Nothing was read into value, so it must not be used */ + if (size >= 0 && size <= value_size) + size = -EIO; + } if (size < 0) { error = size;