On Wed, Nov 1, 2017 at 2:28 AM, Jack Schmidt <busy...@mowsey.org> wrote: > I believe I have found a bug in the current version of busybox. > > When: > * an applet is marked NOEXEC, > * busybox is configured with CONFIG_FEATURE_SH_STANDALONE=y, and > * busybox's ash is asked to do "ENV_VAR=newval no_exec_app" > Then the no_exec app is not called with the new environment. > > This affects git master d5c1482fbac71c51e3add52632cdf1f9f9e6661b and > 1:1.21.0-1ubuntu1 > > To reproduce from git (on linux): > > git pull > make defconfig > sed -i 's/# CONFIG_FEATURE_SH_STANDALONE is not > set/CONFIG_FEATURE_SH_STANDALONE=y/' .config > make > ./busybox ash -c 'BUG=1 head /proc/self/environ | grep -q BUG && echo ok || > echo bug' > ./busybox ash -c 'BUG=1 ./busybox head /proc/self/environ | grep -q BUG && > echo ok || echo bug' > > The first echoes "bug" because the environment is not set.
I reproduced this. The problem here is that /proc/self/environ is not the environment as seen by C code. It is the memory area of the process where *initial environment variables* are stored (IIRC it is located in the top part of the stack area). When NOEXEC applet is executed, the environment *is* set up correctly, but on the C language level: environ[] array is updated. The *initial environment* is not updated. Therefore, /proc/self/environ does not show new added variables. > Alpine linux uses a similar command to check if /proc is really mounted, or > is just a semi-convincing fake. With CONFIG_FEATURE_SH_STANDALONE, real /proc > registers as a fake. Please tell me more. What exactly Alpine is doing. _______________________________________________ busybox mailing list busybox@busybox.net http://lists.busybox.net/mailman/listinfo/busybox
