bionic: fix assorted static analyzer warnings

Warnings:

bionic/libc/bionic/fts.c:722:5: warning: Null passed to a callee that
requires a non-null 1st parameter

bionic/libc/bionic/sched_cpualloc.c:34:25: warning: Result of 'malloc'
is converted to a pointer of type 'cpu_set_t', which is incompatible
with sizeof operand type 'unsigned long'

bionic/linker/linker_main.cpp:315:7: warning: Access to field 'e_type'
results in a dereference of a null pointer (loaded from variable
'elf_hdr')

bionic/linker/linker_main.cpp:493:66: warning: Access to field 'e_phoff'
results in a dereference of a null pointer (loaded from variable
'elf_hdr')

bionic/linker/linker_main.cpp:90:14: warning: Access to field 'next'
results in a dereference of a null pointer (loaded from variable 'prev')

Bug: None
Test: mma; analyzer warnings are gone. CtsBionicTestCases pass.
Change-Id: I699a60c2c6f64c50b9ea06848a680c98a8abb44a

1 files changed, 15 insertions, 0 deletions

diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 5dc215f9d..db3697618 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -87,6 +87,7 @@ bool solist_remove_soinfo(soinfo* si) {
 
   // prev will never be null, because the first entry in solist is
   // always the static libdl_info.
+  CHECK(prev != nullptr);
   prev->next = si->next;
   if (si == sonext) {
     sonext = prev;
@@ -307,6 +308,11 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args) {
       break;
     }
   }
+
+  if (si->base == 0) {
+    async_safe_fatal("Could not find a PHDR: broken executable?");
+  }
+
   si->dynamic = nullptr;
 
   ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(si->base);
@@ -488,6 +494,15 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
   static uintptr_t linktime_addr = reinterpret_cast<uintptr_t>(&linktime_addr);
   ElfW(Addr) linker_addr = reinterpret_cast<uintptr_t>(&linktime_addr) - linktime_addr;
 
+#if defined(__clang_analyzer__)
+  // The analyzer assumes that linker_addr will always be null. Make it an
+  // unknown value so we don't have to mark N places with NOLINTs.
+  //
+  // (`+=`, rather than `=`, allows us to sidestep a potential "unused store"
+  // complaint)
+  linker_addr += reinterpret_cast<uintptr_t>(raw_args);
+#endif
+
   ElfW(Addr) entry_point = args.getauxval(AT_ENTRY);
   ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr);
   ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff);