Help the compiler see we stack allocate a small array. Add assert to check no machine prefix is ever larger than 16. Current maximum number is 7. This prevents gcc warning about possible unbounded stack usage with -Wstack-usage.
Signed-off-by: Mark Wielaard <[email protected]> --- libebl/ChangeLog | 5 +++++ libebl/eblopenbackend.c | 10 ++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/libebl/ChangeLog b/libebl/ChangeLog index 3655e72..9ca7b47 100644 --- a/libebl/ChangeLog +++ b/libebl/ChangeLog @@ -1,3 +1,8 @@ +2015-05-17 Mark Wielaard <[email protected]> + + * eblopenbackend.c (MAX_PREFIX_LEN): New define (16). + (openbackend): Stack allocate symname array using MAX_PREFIX_LEN. + 2015-01-27 Mark Wielaard <[email protected]> * libebl.h: Add comment from README that this is completely diff --git a/libebl/eblopenbackend.c b/libebl/eblopenbackend.c index 3a22f53..2766e7b 100644 --- a/libebl/eblopenbackend.c +++ b/libebl/eblopenbackend.c @@ -1,5 +1,5 @@ /* Generate ELF backend handle. - Copyright (C) 2000-2014 Red Hat, Inc. + Copyright (C) 2000-2015 Red Hat, Inc. This file is part of elfutils. This file is free software; you can redistribute it and/or modify @@ -135,6 +135,8 @@ static const struct }; #define nmachines (sizeof (machines) / sizeof (machines[0])) +/* No machine prefix should be larger than this. */ +#define MAX_PREFIX_LEN 16 /* Default callbacks. Mostly they just return the error value. */ static const char *default_object_type_name (int ignore, char *buf, @@ -343,7 +345,11 @@ openbackend (elf, emulation, machine) static const char version[] = MODVERSION; const char *modversion; ebl_bhinit_t initp; - char symname[machines[cnt].prefix_len + sizeof "_init"]; + + // We use a static number to help the compiler see we don't + // overflow the stack with an arbitrary number. + assert (machines[cnt].prefix_len <= MAX_PREFIX_LEN); + char symname[MAX_PREFIX_LEN + sizeof "_init"]; strcpy (mempcpy (symname, machines[cnt].prefix, machines[cnt].prefix_len), "_init"); -- 1.8.3.1
