Reland^2 "[MTE] remap stacks with PROT_MTE when requested by dlopened library"
Also enable stack MTE if main binary links in a library that needs it.
Otherwise the following is possible:
1. a binary doesn't require stack MTE, but links in libraries that use
stg on the stack
2. that binary later dlopens a library that requires stack MTE, and our
logic in dlopen remaps the stacks with MTE
3. the libraries from step 1 now have tagged pointers with missing tags
in memory, so things go wrong
This reverts commit f53e91cc810be2a36377f3b7765f50c89f1f0046.
Reason for revert: Fixed problem detected in b/324568991
Test: atest memtag_stack_dlopen_test with MTE enabled
Test: check crash is gone on fullmte build
Change-Id: I4a93f6814a19683c3ea5fe1e6d455df5459d31e1
diff --git a/linker/linker.cpp b/linker/linker.cpp
index a12388c..b0caedd 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -1695,13 +1695,31 @@
}
// Step 3: pre-link all DT_NEEDED libraries in breadth first order.
+ bool any_memtag_stack = false;
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
if (!si->is_linked() && !si->prelink_image()) {
return false;
}
+ // si->memtag_stack() needs to be called after si->prelink_image() which populates
+ // the dynamic section.
+ if (si->has_min_version(7) && si->memtag_stack()) {
+ any_memtag_stack = true;
+ LD_LOG(kLogDlopen,
+ "... load_library requesting stack MTE for: realpath=\"%s\", soname=\"%s\"",
+ si->get_realpath(), si->get_soname());
+ }
register_soinfo_tls(si);
}
+ if (any_memtag_stack) {
+ if (auto* cb = __libc_shared_globals()->memtag_stack_dlopen_callback) {
+ cb();
+ } else {
+ // find_library is used by the initial linking step, so we communicate that we
+ // want memtag_stack enabled to __libc_init_mte.
+ __libc_shared_globals()->initial_memtag_stack = true;
+ }
+ }
// Step 4: Construct the global group. DF_1_GLOBAL bit is force set for LD_PRELOADed libs because
// they must be added to the global group. Note: The DF_1_GLOBAL bit for a library is normally set