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* [glibc] Correct range checking in mallopt/mxfast/tcache [BZ #25194]
@ 2019-12-05 21:47 DJ Delorie
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From: DJ Delorie @ 2019-12-05 21:47 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=16554464bcd9d77b07c6ff419dc54f00e394fa50
commit 16554464bcd9d77b07c6ff419dc54f00e394fa50
Author: DJ Delorie <dj@redhat.com>
Date: Tue Dec 3 17:44:36 2019 -0500
Correct range checking in mallopt/mxfast/tcache [BZ #25194]
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>
Diff:
---
malloc/malloc.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 70cc35a..7d7d30b 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -5086,13 +5086,14 @@ do_set_arena_max (size_t value)
static __always_inline int
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);
mp_.tcache_max_bytes = value;
mp_.tcache_bins = csize2tidx (request2size(value)) + 1;
+ return 1;
}
- return 1;
+ return 0;
}
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);
mp_.tcache_count = value;
+ return 1;
}
- return 1;
+ return 0;
}
static __always_inline int
@@ -5119,7 +5121,7 @@ static inline int
__always_inline
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 ());
set_max_fast (value);
@@ -5144,18 +5146,24 @@ __libc_mallopt (int param_number, int value)
(see definition of set_max_fast). */
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)
{
case M_MXFAST:
- do_set_mxfast (value);
+ res = do_set_mxfast (value);
break;
case M_TRIM_THRESHOLD:
- do_set_trim_threshold (value);
+ res = do_set_trim_threshold (value);
break;
case M_TOP_PAD:
- do_set_top_pad (value);
+ res = do_set_top_pad (value);
break;
case M_MMAP_THRESHOLD:
@@ -5163,25 +5171,25 @@ __libc_mallopt (int param_number, int value)
break;
case M_MMAP_MAX:
- do_set_mmaps_max (value);
+ res = do_set_mmaps_max (value);
break;
case M_CHECK_ACTION:
- do_set_mallopt_check (value);
+ res = do_set_mallopt_check (value);
break;
case M_PERTURB:
- do_set_perturb_byte (value);
+ res = do_set_perturb_byte (value);
break;
case M_ARENA_TEST:
if (value > 0)
- do_set_arena_test (value);
+ res = do_set_arena_test (value);
break;
case M_ARENA_MAX:
if (value > 0)
- do_set_arena_max (value);
+ res = do_set_arena_max (value);
break;
}
__libc_lock_unlock (av->mutex);
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2019-12-05 21:47 [glibc] Correct range checking in mallopt/mxfast/tcache [BZ #25194] DJ Delorie
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