env_dup: fix copying of parent's env to child with ARCH_ADDRENV=y #6010
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pussuw
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CI error is due to unused label: Will fix it after comments |
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Ensures that when errout_xx is taken, args are freed
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xiaoxiang781216
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Apr 21, 2022
If address environments are in use, it is not possible to simply memcpy from from one process to another. The current implementation of env_dup does precisely this and thus, it fails at once when it is attempted between two user processes. The solution is to use the kernel's heap as an intermediate buffer. This is a simple, effective and common way to do a fork(). Obviously this is not needed for kernel processes.
Now that the environment strings are stored as an array of strings, they can be passed from the application via char **environ, which is really defined as a function call to get_environ_ptr(). This works as is for flat build, but protected mode and kernel mode require a call gate, which is added here.
This keeps backwards compatibility with apps that do not provide envp. The old implementation passes NULL always and this change fixes any regression caused by it.
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I patched two build errors due to missing definition of get_environ_ptr when CONFIG_DISABLE_ENVIRON is defined. |
xiaoxiang781216
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Apr 21, 2022
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Summary
Fixes copying of parent environment to child when address environments are in use. This is done by copying the parent's env into neutral kernel memory first, and from kernel memory to the child.
Impact
Fixes environment variables for ARCH_ADDRENV=y and BUILD_KERNEL=y
Testing
MPFS icicle:knsh