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Correct range checking in mallopt/mxfast/tcache [BZ #25194]

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do_set_tcache_max, do_set_mxfast:
Fix two instances of comparing "size_t < 0"
Both cases have upper limit, so the "negative value" case
is already handled via overflow semantics.

do_set_tcache_max, do_set_tcache_count:
Fix return value on error.  Note: currently not used.

mallopt:
pass return value of helper functions to user.  Behavior should
only be actually changed for mxfast, where we restore the old
(pre-tunables) behavior.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
DJ Delorie
2019-12-03 17:44:36 -05:00
parent 1f7525d924
commit 16554464bc
1 changed files with 20 additions and 12 deletions
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32
malloc/malloc.c
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@ -5086,13 +5086,14 @@ do_set_arena_max (size_t value)
static __always_inline int static __always_inline int
do_set_tcache_max (size_t value) do_set_tcache_max (size_t value)
{ {
if (value >= 0 && value <= MAX_TCACHE_SIZE) if (value <= MAX_TCACHE_SIZE)
{ {
LIBC_PROBE (memory_tunable_tcache_max_bytes, 2, value, mp_.tcache_max_bytes); LIBC_PROBE (memory_tunable_tcache_max_bytes, 2, value, mp_.tcache_max_bytes);
mp_.tcache_max_bytes = value; mp_.tcache_max_bytes = value;
mp_.tcache_bins = csize2tidx (request2size(value)) + 1; mp_.tcache_bins = csize2tidx (request2size(value)) + 1;
}
return 1; return 1;
}
return 0;
} }
static __always_inline int static __always_inline int
@ -5102,8 +5103,9 @@ do_set_tcache_count (size_t value)
{ {
LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count); LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count);
mp_.tcache_count = value; mp_.tcache_count = value;
}
return 1; return 1;
}
return 0;
} }
static __always_inline int static __always_inline int
@ -5119,7 +5121,7 @@ static inline int
__always_inline __always_inline
do_set_mxfast (size_t value) do_set_mxfast (size_t value)
{ {
if (value >= 0 && value <= MAX_FAST_SIZE) if (value <= MAX_FAST_SIZE)
{ {
LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ()); LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ());
set_max_fast (value); set_max_fast (value);
@ -5144,18 +5146,24 @@ __libc_mallopt (int param_number, int value)
(see definition of set_max_fast). */ (see definition of set_max_fast). */
malloc_consolidate (av); malloc_consolidate (av);
/* Many of these helper functions take a size_t. We do not worry
about overflow here, because negative int values will wrap to
very large size_t values and the helpers have sufficient range
checking for such conversions. Many of these helpers are also
used by the tunables macros in arena.c. */
switch (param_number) switch (param_number)
{ {
case M_MXFAST: case M_MXFAST:
do_set_mxfast (value); res = do_set_mxfast (value);
break; break;
case M_TRIM_THRESHOLD: case M_TRIM_THRESHOLD:
do_set_trim_threshold (value); res = do_set_trim_threshold (value);
break; break;
case M_TOP_PAD: case M_TOP_PAD:
do_set_top_pad (value); res = do_set_top_pad (value);
break; break;
case M_MMAP_THRESHOLD: case M_MMAP_THRESHOLD:
@ -5163,25 +5171,25 @@ __libc_mallopt (int param_number, int value)
break; break;
case M_MMAP_MAX: case M_MMAP_MAX:
do_set_mmaps_max (value); res = do_set_mmaps_max (value);
break; break;
case M_CHECK_ACTION: case M_CHECK_ACTION:
do_set_mallopt_check (value); res = do_set_mallopt_check (value);
break; break;
case M_PERTURB: case M_PERTURB:
do_set_perturb_byte (value); res = do_set_perturb_byte (value);
break; break;
case M_ARENA_TEST: case M_ARENA_TEST:
if (value > 0) if (value > 0)
do_set_arena_test (value); res = do_set_arena_test (value);
break; break;
case M_ARENA_MAX: case M_ARENA_MAX:
if (value > 0) if (value > 0)
do_set_arena_max (value); res = do_set_arena_max (value);
break; break;
} }
__libc_lock_unlock (av->mutex); __libc_lock_unlock (av->mutex);