52dc0595d5
__ex_table is a simple table section where each entry is a pair of addresses - the first address is an address which can fault in kernel space, and the second address points to where the kernel should jump to when handling that fault. This is how copy_from_user() does not crash the kernel if userspace gives a borked pointer for example. If one of these addresses point to a non-executable section, something is seriously wrong since it either means the kernel will never fault from there or it will not be able to jump to there. As both cases are serious enough, we simply error out in these cases so the build fails and the developper has to fix the issue. In case the section is executable, but it isn't referenced in our list of authorized sections to point to from __ex_table, we just dump a warning giving more information about it. We do this in case the new section is executable but isn't supposed to be executed by the kernel. This happened with .altinstr_replacement, which is executable but is only used to copy instructions from - we should never have our instruction pointer pointing in .altinstr_replacement. Admitedly, a proper fix in that case would be to just set .altinstr_replacement NX, but we need to warn about future cases like this. Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (added long casts) |
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| .. | ||
| .gitignore | ||
| devicetable-offsets.c | ||
| empty.c | ||
| file2alias.c | ||
| Makefile | ||
| mk_elfconfig.c | ||
| modpost.c | ||
| modpost.h | ||
| sumversion.c | ||