Add ZSWAP_MAX_KPARAM_NAME define and change the "zpool" and "compressor" kparams maxlen to use the define. Update the param set function to use a char[ZSWAP_MAX_KPARAM_NAME] instead of a variable-sized char[].
The kbuild test robot reported: >> mm/zswap.c:759:1: warning: '__zswap_param_set' uses dynamic stack >> allocation which was a variable-sized char[] allocation on the stack: char str[kp->str->maxlen], *s; This technically was ok, as there are only 2 possible kparams sent to this function, and both of them have their maxlen set low (to 32 or 64), but this patch simplifies and clarifies things by creating a single define to use for the kparam maxlen and the size of the stack char[]. Reported-by: kbuild test robot <[email protected]> Signed-off-by: Dan Streetman <[email protected]> --- mm/zswap.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index 4043df7..d74872e 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -80,12 +80,15 @@ static u64 zswap_duplicate_entry; static bool zswap_enabled; module_param_named(enabled, zswap_enabled, bool, 0644); +/* This should be >= CRYPTO_MAX_ALG_NAME and ZPOOL_MAX_TYPE_NAME */ +#define ZSWAP_MAX_KPARAM_NAME 64 + /* Crypto compressor to use */ #define ZSWAP_COMPRESSOR_DEFAULT "lzo" -static char zswap_compressor[CRYPTO_MAX_ALG_NAME] = ZSWAP_COMPRESSOR_DEFAULT; +static char zswap_compressor[ZSWAP_MAX_KPARAM_NAME] = ZSWAP_COMPRESSOR_DEFAULT; static struct kparam_string zswap_compressor_kparam = { .string = zswap_compressor, - .maxlen = sizeof(zswap_compressor), + .maxlen = ZSWAP_MAX_KPARAM_NAME, }; static int zswap_compressor_param_set(const char *, const struct kernel_param *); @@ -98,10 +101,10 @@ module_param_cb(compressor, &zswap_compressor_param_ops, /* Compressed storage zpool to use */ #define ZSWAP_ZPOOL_DEFAULT "zbud" -static char zswap_zpool_type[32 /* arbitrary */] = ZSWAP_ZPOOL_DEFAULT; +static char zswap_zpool_type[ZSWAP_MAX_KPARAM_NAME] = ZSWAP_ZPOOL_DEFAULT; static struct kparam_string zswap_zpool_kparam = { .string = zswap_zpool_type, - .maxlen = sizeof(zswap_zpool_type), + .maxlen = ZSWAP_MAX_KPARAM_NAME, }; static int zswap_zpool_param_set(const char *, const struct kernel_param *); static struct kernel_param_ops zswap_zpool_param_ops = { @@ -688,14 +691,12 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp, char *type, char *compressor) { struct zswap_pool *pool, *put_pool = NULL; - char str[kp->str->maxlen], *s; + char str[ZSWAP_MAX_KPARAM_NAME], *s; int ret; - /* - * kp is either zswap_zpool_kparam or zswap_compressor_kparam, defined - * at the top of this file, so maxlen is CRYPTO_MAX_ALG_NAME (64) or - * 32 (arbitrary). - */ + if (WARN_ON(kp->str->maxlen > ZSWAP_MAX_KPARAM_NAME)) + return -EINVAL; + strlcpy(str, val, kp->str->maxlen); s = strim(str); @@ -1228,6 +1229,9 @@ static int __init init_zswap(void) { struct zswap_pool *pool; + BUILD_BUG_ON(ZSWAP_MAX_KPARAM_NAME < CRYPTO_MAX_ALG_NAME); + BUILD_BUG_ON(ZSWAP_MAX_KPARAM_NAME < ZPOOL_MAX_TYPE_NAME); + zswap_init_started = true; if (zswap_entry_cache_create()) { -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
