Enabling CONFIG_UBSAN=y, below runtime warning occurs both in sandbox and R-Car H3 Salvator-X U-Boot:
===================================================================== UBSAN: Undefined behaviour in lib/hashtable.c:784:8 variable length array bound value 0 <= 0 =====================================================================
It has a slightly different wording when compiling sandbox U-Boot with "gcc-8 -fsanitize=undefined -lubsan":
-----8<----- lib/hashtable.c:784:8: runtime error: \ variable length array bound evaluates to non-positive value 0 -----8<-----
Inspired from v4.11-rc1 commit 620711944459 ("crypto: algif_hash - avoid zero-sized array"), which fixes the same type of UB.
Fixes: d5370febbcbc ("env: delete selected vars not present in imported env") Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com ---
Changes in v2: - Switch to a more elegant solution, inspired from v4.11-rc1 commit 620711944459 ("crypto: algif_hash - avoid zero-sized array") - Shorten the summary line - Drop Reviewed-by due to updates --- include/search.h | 2 +- lib/hashtable.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/search.h b/include/search.h index 5d07b49073cc..417dacdb4482 100644 --- a/include/search.h +++ b/include/search.h @@ -99,7 +99,7 @@ extern ssize_t hexport_r(struct hsearch_data *__htab, */ extern int himport_r(struct hsearch_data *__htab, const char *__env, size_t __size, const char __sep, - int __flag, int __crlf_is_lf, int nvars, + int __flag, int __crlf_is_lf, unsigned int nvars, char * const vars[]);
/* Walk the whole table calling the callback on each element */ diff --git a/lib/hashtable.c b/lib/hashtable.c index 1c48692b69ed..e01a42993dd3 100644 --- a/lib/hashtable.c +++ b/lib/hashtable.c @@ -778,10 +778,10 @@ static int drop_var_from_set(const char *name, int nvars, char * vars[])
int himport_r(struct hsearch_data *htab, const char *env, size_t size, const char sep, int flag, - int crlf_is_lf, int nvars, char * const vars[]) + int crlf_is_lf, unsigned int nvars, char * const vars[]) { char *data, *sp, *dp, *name, *value; - char *localvars[nvars]; + char *localvars[nvars ? : 1]; int i;
/* Test for correct arguments. */