diff options
| author | Mitch Phillips <mitchp@google.com> | 2021-01-20 11:25:11 -0800 |
|---|---|---|
| committer | Mitch Phillips <mitchp@google.com> | 2021-01-20 12:45:07 -0800 |
| commit | 347b01b58324516941b338614dec33cc59c6e018 (patch) | |
| tree | b67214d52098360a8ac78e3056bf32654cf19aa2 /libc | |
| parent | d65b31fad659b806401201adb3cd1dcbf38e61e3 (diff) | |
| download | bionic-347b01b58324516941b338614dec33cc59c6e018.tar.gz | |
[MTE] Change scudo init order to get correct PROT_MTE pages.
scudo_malloc_* for fill contents in __libc_init_scudo calls scudo's
initializers. We haven't told Scudo whether we want MTE-capable (i.e.
mapped with PROT_MTE) size class regions yet, which happens in
SetDefaultHeapTaggingLevel. This can lead to inconsistent mappings,
where processes without ELF notes get the base region with PROT_MTE
(which is undesirable because the performance implications are not
known).
Make sure that scudo is informed of whether regions need to be mapped
PROT_MTE or not by hoising the tagging level up.
Bug: 135772972
Bug: 172365548
Test: On FVP - 'adb shell MEMTAG_OPTIONS=off sanitizer-status' should
have no PROT_MTE mappings (validation by looking for no 'mt' under
'VmFlags:' in /proc/smaps').
Change-Id: Idad64479c4a9459cb40dd211fe942437f8ca16fd
Diffstat (limited to 'libc')
| -rw-r--r-- | libc/bionic/libc_init_common.cpp | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/libc/bionic/libc_init_common.cpp b/libc/bionic/libc_init_common.cpp index f2c3f1c68..01cd2e591 100644 --- a/libc/bionic/libc_init_common.cpp +++ b/libc/bionic/libc_init_common.cpp @@ -87,6 +87,11 @@ static void arc4random_fork_handler() { } void __libc_init_scudo() { + // Heap tagging level *must* be set before interacting with Scudo, otherwise + // the primary will be mapped with PROT_MTE even if MTE is is not enabled in + // this process. + SetDefaultHeapTaggingLevel(); + // TODO(b/158870657) make this unconditional when all devices support SCUDO. #if defined(USE_SCUDO) #if defined(SCUDO_PATTERN_FILL_CONTENTS) @@ -95,7 +100,6 @@ void __libc_init_scudo() { scudo_malloc_set_zero_contents(1); #endif #endif - SetDefaultHeapTaggingLevel(); } __BIONIC_WEAK_FOR_NATIVE_BRIDGE |