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Add definition of M_MEMTAG_TUNING.

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Bug: 191769584
Test: N/A
Merged-In: Ief77f95a04411528563787a9fc6d10738fc5688f
Change-Id: Ief77f95a04411528563787a9fc6d10738fc5688f
(cherry picked from commit d8d561c984)
This commit is contained in:
Evgenii Stepanov 2021-06-22 10:18:12 -07:00
parent 29045b3d7b
commit a44aa2e138
1 changed files with 41 additions and 2 deletions
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43
libc/include/malloc.h
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@ -170,7 +170,45 @@ int malloc_info(int __must_be_zero, FILE* __fp) __INTRODUCED_IN(23);
* Available since API level 28.
*/
#define M_PURGE (-101)
/*
/**
* mallopt() option to tune the allocator's choice of memory tags to
* make it more likely that a certain class of memory errors will be
* detected. This is only relevant if MTE is enabled in this process
* and ignored otherwise. The value argument should be one of the
* M_MEMTAG_TUNING_* flags.
* NOTE: This is only available in scudo.
*
* Available since API level 31.
*/
#define M_MEMTAG_TUNING (-102)
/**
* When passed as a value of M_MEMTAG_TUNING mallopt() call, enables
* deterministic detection of linear buffer overflow and underflow
* bugs by assigning distinct tag values to adjacent allocations. This
* mode has a slightly reduced chance to detect use-after-free bugs
* because only half of the possible tag values are available for each
* memory location.
*
* Please keep in mind that MTE can not detect overflow within the
* same tag granule (16-byte aligned chunk), and can miss small
* overflows even in this mode. Such overflow can not be the cause of
* a memory corruption, because the memory within one granule is never
* used for multiple allocations.
*/
#define M_MEMTAG_TUNING_BUFFER_OVERFLOW 0
/**
* When passed as a value of M_MEMTAG_TUNING mallopt() call, enables
* independently randomized tags for uniform ~93% probability of
* detecting both spatial (buffer overflow) and temporal (use after
* free) bugs.
*/
#define M_MEMTAG_TUNING_UAF 1
/**
* mallopt() option for per-thread memory initialization tuning.
* The value argument should be one of:
* 1: Disable automatic heap initialization and, where possible, memory tagging,
@ -210,7 +248,7 @@ int malloc_info(int __must_be_zero, FILE* __fp) __INTRODUCED_IN(23);
* should not be zero-initialized, any other value indicates to initialize heap
* memory to zero.
*
* Note that this memory mitigations is only implemented in scudo and therefore
* Note that this memory mitigation is only implemented in scudo and therefore
* this will have no effect when using another allocator (such as jemalloc on
* Android Go devices).
*
@ -222,6 +260,7 @@ int malloc_info(int __must_be_zero, FILE* __fp) __INTRODUCED_IN(23);
* mallopt() option to change the heap tagging state. May be called at any
* time, including when multiple threads are running.
* The value must be one of the M_HEAP_TAGGING_LEVEL_ constants.
* NOTE: This is only available in scudo.
*
* Available since API level 31.
*/