On Thu, Jun 06, 2024 at 03:31:49PM +0200, Daniel v. Kirschten wrote:
If a module is being loaded, and the .gnu.linkonce.this_module section
in the module's ELF file does not have the WRITE flag, the kernel will
map the finished module struct of that module as read-only.
This causes a kernel panic when the struct is written to the first time
after it has been marked read-only. Currently this happens in
complete_formation in kernel/module/main.c:2765 when the module's state is
set to MODULE_STATE_COMING, just after setting up the memory protections.
How did you find this issue?
Down the line, this seems to lead to unpredictable freezes when trying to
load other modules - I guess this is due to some structures not being
cleaned up properly, but I didn't investigate this further.
A check already exists which verifies that .gnu.linkonce.this_module
is ALLOC. This patch simply adds an analogous check for WRITE.
Can you check to ensure our modules generated have a respective check to
ensure this check exists at build time? That would proactively inform
userspace when a built module is not built correctly, and the tool
responsible can be identified.