busybox: disable CONFIG_FEATURE_CLEAN_UP in default configs

FEATURE_CLEAN_UP is a configuration feature to get busybox to explicitly call free() on dynamic allocated memory just before exiting so memory leak detectors like valgrind don't get confused. Upstream explicitly recommends to NOT enable this option:

config FEATURE_CLEAN_UP
bool "Clean up all memory before exiting (usually not needed)" default n
help
As a size optimization, busybox normally exits without explicitly freeing dynamically allocated memory or closing files. This saves space since the OS will clean up for us, but it can confuse debuggers like valgrind, which report tons of memory and resource leaks.

Don't enable this unless you have a really good reason to clean things up manually.

Having this option enabled adds a bit of bloat, but more significantly these cleanup code paths don't get tested very often so some times get out of sync with the allocation code which can lead to crashes (or security issues from double frees), so it is safer to disable the option.

For people wanting to debug memory leak issues with busybox, the option can still be enabled with a configuration fragment (or a custom config).

The size difference isn't huge (br-arm-full-static):

(quoted diff) +0 -2

-rwxr-xr-x 1 peko peko 886K Jul  5 10:56 output-busybox1/target/bin/busybox
-rwxr-xr-x 1 peko peko 882K Jul  5 10:53 output-busybox2/target/bin/busybox

Signed-off-by Peter Korsgaard <[email protected]>

---
 package/busybox/busybox-minimal.config | 2 +-
 package/busybox/busybox.config         | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

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"Peter" == Peter Korsgaard <[email protected]> writes:

FEATURE_CLEAN_UP is a configuration feature to get busybox to explicitly call free() on dynamic allocated memory just before exiting so memory leak detectors like valgrind don't get confused. Upstream explicitly recommends to NOT enable this option:

config FEATURE_CLEAN_UP
bool "Clean up all memory before exiting (usually not needed)" default n
help
As a size optimization, busybox normally exits without explicitly freeing dynamically allocated memory or closing files. This saves space since the OS will clean up for us, but it can confuse debuggers like valgrind, which report tons of memory and resource leaks.

Don't enable this unless you have a really good reason to clean things up manually.

Having this option enabled adds a bit of bloat, but more significantly these cleanup code paths don't get tested very often so some times get out of sync with the allocation code which can lead to crashes (or security issues from double frees), so it is safer to disable the option.

For people wanting to debug memory leak issues with busybox, the option can still be enabled with a configuration fragment (or a custom config).

The size difference isn't huge (br-arm-full-static):

(quoted diff) +0 -2

-rwxr-xr-x 1 peko peko 886K Jul  5 10:56 output-busybox1/target/bin/busybox
-rwxr-xr-x 1 peko peko 882K Jul  5 10:53 output-busybox2/target/bin/busybox

Signed-off-by Peter Korsgaard <[email protected]>