diff options
| -rw-r--r-- | lib/asan/asan_mapping.h | 3 | ||||
| -rw-r--r-- | lib/asan/asan_rtl.cc | 14 |
2 files changed, 16 insertions, 1 deletions
diff --git a/lib/asan/asan_mapping.h b/lib/asan/asan_mapping.h index 8b4857e6d..937c57b28 100644 --- a/lib/asan/asan_mapping.h +++ b/lib/asan/asan_mapping.h @@ -178,7 +178,8 @@ static const u64 kWindowsShadowOffset32 = 3ULL << 28; // 0x30000000 // With the zero shadow base we can not actually map pages starting from 0. // This constant is somewhat arbitrary. -#define kZeroBaseShadowStart 4096 +#define kZeroBaseShadowStart 0 +#define kZeroBaseMaxShadowStart (1 << 18) #define kShadowGapBeg (kLowShadowEnd ? kLowShadowEnd + 1 \ : kZeroBaseShadowStart) diff --git a/lib/asan/asan_rtl.cc b/lib/asan/asan_rtl.cc index 4fa8ea2f0..7ff657bc5 100644 --- a/lib/asan/asan_rtl.cc +++ b/lib/asan/asan_rtl.cc @@ -301,6 +301,20 @@ static void ProtectGap(uptr addr, uptr size) { void *res = MmapNoAccess(addr, size, "shadow gap"); if (addr == (uptr)res) return; + // A few pages at the start of the address space can not be protected. + // But we really want to protect as much as possible, to prevent this memory + // being returned as a result of a non-FIXED mmap(). + if (addr == kZeroBaseShadowStart) { + uptr step = GetPageSizeCached(); + while (size > step && addr < kZeroBaseMaxShadowStart) { + addr += step; + size -= step; + void *res = MmapNoAccess(addr, size, "shadow gap"); + if (addr == (uptr)res) + return; + } + } + Report("ERROR: Failed to protect the shadow gap. " "ASan cannot proceed correctly. ABORTING.\n"); DumpProcessMap(); |