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Fixed the returned original address from dlhook on ARM

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This commit is contained in:
Patrick Gaskin
2020-04-22 02:28:08 -04:00
parent ac55fd5bf1
commit be1a40d524
1 changed files with 6 additions and 1 deletions
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7
src/dlhook.c
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@@ -86,6 +86,11 @@ void *nmi_dlhook(void *handle, const char *symname, void *target, char **err_out
NMI_ASSERT(ELFW(ST_TYPE)(sym->st_info) == STT_FUNC, "not a function symbol (ST_TYPE=%d) (gotoff=%p)", ELFW(ST_TYPE)(sym->st_info), (void*)(rel->r_offset));
NMI_ASSERT(ELFW(ST_BIND)(sym->st_info) == STB_GLOBAL, "not a globally bound symbol (ST_BIND=%d) (gotoff=%p)", ELFW(ST_BIND)(sym->st_info), (void*)(rel->r_offset));
// TODO: figure out why directly getting the offset from the GOT was broken on ARM, but not x86
NMI_LOG("ensuring the symbol is loaded");
void *orig = dlsym(handle, symname);
NMI_ASSERT(orig, "could not dlsym symbol");
// remove memory protection (to bypass RELRO if it is enabled)
// note: this doesn't seem to be used on the Kobo, but we might as well stay on the safe side (plus, I test this on my local machine too)
// note: the only way to read the current memory protection is to parse /proc/maps, but there's no harm in unprotecting it again if it's not protected
@@ -98,7 +103,7 @@ void *nmi_dlhook(void *handle, const char *symname, void *target, char **err_out
// replace the target offset
NMI_LOG("patching symbol");
void *orig = *gotoff;
//void *orig = *gotoff;
*gotoff = target;
NMI_LOG("successfully patched symbol %s (orig=%p, new=%p)", str, orig, target);
NMI_RETURN_OK(orig);