From: Simon Glass <simon.glass@canonical.com> When mcheck is enabled, malloc_usable_size() returns incorrect results because mem2chunk() is called on the offset user pointer rather than the actual chunk. The pointer returned to the user is offset by the mcheck header, but malloc_usable_size() is unaware of this. Add a wrapper that returns the user-requested size stored in the mcheck header. This fixes test failures when CONFIG_MCHECK_CALLER_LEN is set to larger values. Also add a wrapper for the case where MALLOC_DEBUG is enabled without MCHECK_HEAP_PROTECTION, since MALLOC_DEBUG makes dlmalloc_usable_size_impl() static but no public dlmalloc_usable_size exists outside the mcheck block. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com> --- common/dlmalloc.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/common/dlmalloc.c b/common/dlmalloc.c index 78efdf5fd9a..71f81aeaec7 100644 --- a/common/dlmalloc.c +++ b/common/dlmalloc.c @@ -648,6 +648,7 @@ static inline void MALLOC_COPY(void *dest, const void *src, size_t sz) { memcpy( #define dlrealloc_impl dlrealloc #define dlmemalign_impl dlmemalign #define dlcalloc_impl dlcalloc +#define dlmalloc_usable_size_impl dlmalloc_usable_size #endif static bool malloc_testing; /* enable test mode */ @@ -5943,13 +5944,15 @@ int dlmallopt(int param_number, int value) { return change_mparam(param_number, value); } -size_t dlmalloc_usable_size(const void* mem) { - if (mem != 0) { - mchunkptr p = mem2chunk((void*)mem); - if (is_inuse(p)) - return chunksize(p) - overhead_for(p); - } - return 0; +STATIC_IF_MCHECK size_t dlmalloc_usable_size_impl(const void *mem) +{ + if (mem != 0) { + mchunkptr p = mem2chunk((void *)mem); + + if (is_inuse(p)) + return chunksize(p) - overhead_for(p); + } + return 0; } #if CONFIG_IS_ENABLED(MCHECK_HEAP_PROTECTION) @@ -6098,6 +6101,20 @@ void *dlcalloc(size_t n, size_t elem_size) return mcheck_alloc_noclean_posthook(p, n * elem_size, mcheck_caller()); } +size_t dlmalloc_usable_size(const void *mem) +{ + if (!mem) + return 0; + + if (mcheck_disabled) + return dlmalloc_usable_size_impl(mem); + + /* Return the user-requested size from mcheck header */ + const struct mcheck_hdr *hdr = &((const struct mcheck_hdr *)mem)[-1]; + + return hdr->size; +} + /* mcheck API */ int mcheck_pedantic(mcheck_abortfunc_t f) { @@ -6145,6 +6162,14 @@ void *dlcalloc(size_t n, size_t elem_size) } #endif /* MCHECK_HEAP_PROTECTION */ +#if CONFIG_IS_ENABLED(MALLOC_DEBUG) && !CONFIG_IS_ENABLED(MCHECK_HEAP_PROTECTION) +/* Wrapper needed when MALLOC_DEBUG makes dlmalloc_usable_size_impl static */ +size_t dlmalloc_usable_size(const void *mem) +{ + return dlmalloc_usable_size_impl(mem); +} +#endif + #if !CONFIG_IS_ENABLED(MCHECK_HEAP_PROTECTION) /* Stub when mcheck is not enabled */ void mcheck_set_disabled(bool disabled) -- 2.43.0