If the find_fromsym() call fails and returns NULL, the warn() call will dereference this NULL pointer and cause the program to crash. This happened when I tried to build with "test_user_copy" module. With this fix, it prints lots of warnings like this: WARNING: modpost: lib/test_user_copy: section mismatch in reference: (unknown)+0x4 (section: .text.fixup) -> (unknown) (section: .init.text) masahiroy@kernel.org: The issue is reproduced with ARCH=arm allnoconfig + CONFIG_MODULES=y + CONFIG_RUNTIME_TESTING_MENU=y + CONFIG_TEST_USER_COPY=m
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| @@ -1050,7 +1050,9 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf, · 1049 unmodified lines | |||
| 1050 | sec_mismatch_count++; | 1050 | sec_mismatch_count++; |
| 1051 | 1051 | ||
| 1052 | warn("%s: section mismatch in reference: %s+0x%x (section: %s) -> %s (section: %s)\n", | 1052 | warn("%s: section mismatch in reference: %s+0x%x (section: %s) -> %s (section: %s)\n", |
| 1053 | modname, fromsym, (unsigned int)(faddr - from->st_value), fromsec, tosym, tosec); | 1053 | modname, fromsym, |
| 1054 | (unsigned int)(faddr - (from ? from->st_value : 0)), | ||
| 1055 | fromsec, tosym, tosec); | ||
| 1054 | 1056 | ||
| 1055 | if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) { | 1057 | if (mismatch->mismatch == EXTABLE_TO_NON_TEXT) { |
| 1056 | if (match(tosec, mismatch->bad_tosec)) | 1058 | if (match(tosec, mismatch->bad_tosec)) |