From b171466c445dbdd39d5084dd4e4c138a7051d99a Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Thu, 15 Sep 2016 10:58:28 +0200 Subject: [PATCH] toolchain-external: fix potential entire root filesystem removal This reverts commit a0aa7e0e1750f6ace2879ea8adb1425a41431b79 and reworks the code to fix a major and potentially catastrophic bug when the following conditions are met: - The user has selected a "known toolchain profile", such as a Linaro toolchain, a Sourcery CodeBench toolchain etc. People using "custom toolchain profile" are not affected. - The user has enabled BR2_TOOLCHAIN_EXTERNAL_PREINSTALLED=y to indicate that the toolchain is already locally available (as opposed to having Buildroot download and extract the toolchain) - The user has left BR2_TOOLCHAIN_EXTERNAL_PATH empty, because his toolchain is directly available through the PATH environment variable. When BR2_TOOLCHAIN_EXTERNAL_PATH is non-empty, Buildroot will do something silly (remove the toolchain contents), but that are limited to the toolchain itself. When such conditions are met, Buildroot will run "rm -rf /*" due to TOOLCHAIN_EXTERNAL_INSTALL_DIR being empty. This bug does not exist in 2016.05, and appeared in 2016.08 due to commit a0aa7e0e1750f6ace2879ea8adb1425a41431b79. Commit a0aa7e0e1750f6ace2879ea8adb1425a41431b79 removed the assignment of TOOLCHAIN_EXTERNAL_SOURCE and TOOLCHAIN_EXTERNAL_SITE to empty, as part of a global cleanup to remove such assignments that supposedly had become unneeded following a fix of the package infrastructure (75630eba22b20d6140a5b58a6d1e35598fb3c0d3: core: do not attempt downloads with no _VERSION set). However, this causes TOOLCHAIN_EXTERNAL_SOURCE to be non-empty even for BR2_TOOLCHAIN_EXTERNAL_PREINSTALLED=y configuration, with the following consequences: - Buildroot downloads the toolchain tarball (while we're saying the toolchain is already available). Not dramatic, but clearly buggy. - Buildroot registers a post-extract hook that moves the toolchain from its extract directory (output/build/toolchain-external-.../ to its final location in host/opt/ext-toolchain/). Before doing this, it removes everything in TOOLCHAIN_EXTERNAL_INSTALL_DIR (which should normally be host/opt/ext-toolchain/). Another mistake that caused the bug is commit b731dc7bfb9c8ce7be502711f0b44ccab5515f1d ("toolchain-external: make extraction idempotent"), which introduce the dangerous call "rm -rf $(var)/*", which can be catastrophic if by mistake $(var) is empty. Instead, this commit should have just used rm -rf $(var) to remove the directory instead: it would have failed without consequences if $(var) is empty, and the directory was anyway already re-created right after with a mkdir. To address this problem, we: - Revert commit a0aa7e0e1750f6ace2879ea8adb1425a41431b79, so that _SOURCE and _SITE are empty in the pre-installed toolchain case. - Rework the code to ensure that similar problems will no happen in the future, by: - Registering the TOOLCHAIN_EXTERNAL_MOVE hook only when BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y, since moving the toolchain is only needed when Buildroot downloaded the toolchain. - Introduce a variable TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR which is the path in which Buildroot installs external toolchains when it is in charge of downloading/extracting them. Then, the TOOLCHAIN_EXTERNAL_MOVE hook is changed to use this variable, which is guaranteed to be non-empty. - Replace the removal of the directory contents $(var)/* by removing the directory itself $(var). The directory was anyway already re-created if needed afterwards. Thanks to doing this, if $(var) ever becomes empty, we will do "rm -rf" which will fail and abort the build, and not the catastrophic "rm -rf /*". Reported-by: Mason Cc: Mason Signed-off-by: Thomas Petazzoni Signed-off-by: Peter Korsgaard --- .../toolchain-external/toolchain-external.mk | 22 ++++++++++++++----- 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/toolchain/toolchain-external/toolchain-external.mk b/toolchain/toolchain-external/toolchain-external.mk index 8de324726e..ad258b86be 100644 --- a/toolchain/toolchain-external/toolchain-external.mk +++ b/toolchain/toolchain-external/toolchain-external.mk @@ -138,8 +138,10 @@ TOOLCHAIN_EXTERNAL_LIBS += $(call qstrip,$(BR2_TOOLCHAIN_EXTRA_EXTERNAL_LIBS)) TOOLCHAIN_EXTERNAL_PREFIX = $(call qstrip,$(BR2_TOOLCHAIN_EXTERNAL_PREFIX)) +TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR = $(HOST_DIR)/opt/ext-toolchain + ifeq ($(BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD),y) -TOOLCHAIN_EXTERNAL_INSTALL_DIR = $(HOST_DIR)/opt/ext-toolchain +TOOLCHAIN_EXTERNAL_INSTALL_DIR = $(TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR) else TOOLCHAIN_EXTERNAL_INSTALL_DIR = $(call qstrip,$(BR2_TOOLCHAIN_EXTERNAL_PATH)) endif @@ -454,21 +456,29 @@ TOOLCHAIN_EXTERNAL_ACTUAL_SOURCE_TARBALL ?= \ $(subst -i686-pc-linux-gnu.tar.bz2,.src.tar.bz2,$(subst -i686-pc-linux-gnu-i386-linux.tar.bz2,-i686-pc-linux-gnu.src.tar.bz2,$(TOOLCHAIN_EXTERNAL_SOURCE))) endif +# In fact, we don't need to download the toolchain, since it is already +# available on the system, so force the site and source to be empty so +# that nothing will be downloaded/extracted. +ifeq ($(BR2_TOOLCHAIN_EXTERNAL_PREINSTALLED),y) +TOOLCHAIN_EXTERNAL_SITE = +TOOLCHAIN_EXTERNAL_SOURCE = +endif + TOOLCHAIN_EXTERNAL_ADD_TOOLCHAIN_DEPENDENCY = NO TOOLCHAIN_EXTERNAL_INSTALL_STAGING = YES # Normal handling of downloaded toolchain tarball extraction. -ifneq ($(TOOLCHAIN_EXTERNAL_SOURCE),) +ifeq ($(BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD),y) TOOLCHAIN_EXTERNAL_EXCLUDES = usr/lib/locale/* # As a regular package, the toolchain gets extracted in $(@D), but # since it's actually a fairly special package, we need it to be moved -# into TOOLCHAIN_EXTERNAL_INSTALL_DIR. +# into TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR. define TOOLCHAIN_EXTERNAL_MOVE - rm -rf $(TOOLCHAIN_EXTERNAL_INSTALL_DIR)/* - mkdir -p $(TOOLCHAIN_EXTERNAL_INSTALL_DIR) - mv $(@D)/* $(TOOLCHAIN_EXTERNAL_INSTALL_DIR)/ + rm -rf $(TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR) + mkdir -p $(TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR) + mv $(@D)/* $(TOOLCHAIN_EXTERNAL_DOWNLOAD_INSTALL_DIR)/ endef TOOLCHAIN_EXTERNAL_POST_EXTRACT_HOOKS += \ TOOLCHAIN_EXTERNAL_MOVE