Messages in this thread | | | Date | Mon, 9 Jun 2003 03:14:49 -0700 | From | "Adam J. Richter" <> | Subject | 2.5.70-bk1[23]: load_module crashes when aborting module load |
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Hi Rusty,
I thought I should report this problem to you now, as I'm about to have to explore some code that I'm not too familiar with (vfree) as I continue debugging it. Also note I am running a modified kernel/module.c, so it is remotely possible that this problem is self-inflicted, but I don't think so.
In 2.5.70-bk1[23], I get a kernel bad memory reference when trying load a module with an undefined symbol that is not found. The bad memory reference occurs in load_module after the call to module_free(mod,mod->module_core), the next time that "mod" is dereferenced. Here is a commented excerpt from load_module in kernel/module.c:
cleanup: module_unload_free(mod); module_free(mod, mod->module_init); free_core: module_free(mod, mod->module_core); /* The following "if" statement generates a kernel bad memory reference. --Adam */ free_percpu: if (mod->percpu) percpu_modfree(mod->percpu);
For whatever reason, module->module_core (ee820000) points to an address slightly before mod (mod = ee828780, the bad dereference is to ee8298a4). On x86, module_free() is vfree(). I suspect that somehow vfree() has gotten confused.
By the way, there also seems to be a bug in the 2.5.70-bk12/kernel/module.c changes where mod->percpu is left unitialized if a module has no per-cpu data. I've verified that there really is a junk non-zero value in mod->percpu in that case. However, fixing that bug does not eliminate this problem.
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