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Fix range check in do_tunable_update_val

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Current implementation of tunables does not set arena_max and arena_test
values. Any value provided by glibc.malloc.arena_max and
glibc.malloc.arena_test parameters is ignored.

These tunables have minval value set to 1 (see elf/dl-tunables.list file)
and undefined maxval value. In that case default value (which is 0. see
scripts/gen-tunables.awk) is being used to set maxval.

For instance, generated tunable_list[] entry for arena_max is:
(gdb) p *cur
$1 = {name = 0x7ffff7df6217 "glibc.malloc.arena_max",
 type = {type_code = TUNABLE_TYPE_SIZE_T, min = 1, max = 0},
  val = {numval = 0, strval = 0x0}, initialized = false,
   security_level = TUNABLE_SECLEVEL_SXID_IGNORE,
    env_alias = 0x7ffff7df622e "MALLOC_ARENA_MAX"}

As a result, any value of glibc.malloc.arena_max is ignored by
TUNABLE_SET_VAL_IF_VALID_RANGE macro
  __type min = (__cur)->type.min;                    <- initialized to 1
  __type max = (__cur)->type.max;                    <- initialized to 0!
  if (min == max)                                    <- false
    {
      min = __default_min;
      max = __default_max;
    }
  if ((__type) (__val) >= min && (__type) (val) <= max)  <- false
    {
      (__cur)->val.numval = val;
      (__cur)->initialized = true;
    }

Assigning correct min/max values at a build time fixes a problem.
Plus, a bit of optimization: Setting of default min/max values for the
given type at a run time might be eliminated.

	* elf/dl-tunables.c (do_tunable_update_val): Range checking fix.
	* scripts/gen-tunables.awk: Set unspecified minval and/or maxval
	values to correct default value for given type.
This commit is contained in:
Alexey Makhalov
2017-09-27 02:44:09 +05:30
committed by Siddhesh Poyarekar
parent 592d5c7539
commit cebcb9f864
3 changed files with 20 additions and 13 deletions
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12
scripts/gen-tunables.awk
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@ -1,6 +1,14 @@
# Generate dl-tunable-list.h from dl-tunables.list
BEGIN {
min_of["STRING"]="0"
max_of["STRING"]="0"
min_of["INT_32"]="INT32_MIN"
max_of["INT_32"]="INT32_MAX"
min_of["UINT_64"]="0"
max_of["UINT_64"]="UINT64_MAX"
min_of["SIZE_T"]="0"
max_of["SIZE_T"]="SIZE_MAX"
tunable=""
ns=""
top_ns=""
@ -43,10 +51,10 @@ $1 == "}" {
types[top_ns,ns,tunable] = "STRING"
}
if (!minvals[top_ns,ns,tunable]) {
minvals[top_ns,ns,tunable] = "0"
minvals[top_ns,ns,tunable] = min_of[types[top_ns,ns,tunable]]
}
if (!maxvals[top_ns,ns,tunable]) {
maxvals[top_ns,ns,tunable] = "0"
maxvals[top_ns,ns,tunable] = max_of[types[top_ns,ns,tunable]]
}
if (!env_alias[top_ns,ns,tunable]) {
env_alias[top_ns,ns,tunable] = "NULL"