linker: disallow W + E PT_LOAD segments
No mapped segment from the elf file can be writable and
executable at the same time. This commit adds a check
for malformed PT_LOAD segments in the elf-files.
Bug: http://b/30146890
Test: run bionic-unit-tests --gtest_filter=dlfcn.*
Change-Id: Ia23acbe5a48780b65d7e4a50bbe024cd528079f4
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index c41f3a0..bced722 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -604,9 +604,16 @@
}
if (file_length != 0) {
+ int prot = PFLAGS_TO_PROT(phdr->p_flags);
+ // W + E PT_LOAD segments are not allowed.
+ if ((prot & (PROT_EXEC | PROT_WRITE)) == (PROT_EXEC | PROT_WRITE)) {
+ DL_ERR_AND_LOG("\"%s\": W + E load segments are not allowed", name_.c_str());
+ return false;
+ }
+
void* seg_addr = mmap64(reinterpret_cast<void*>(seg_page_start),
file_length,
- PFLAGS_TO_PROT(phdr->p_flags),
+ prot,
MAP_FIXED|MAP_PRIVATE,
fd_,
file_offset_ + file_page_start);