śr., 13 mar 2019 o 10:45 Anton Ivanov <anton.iva...@cambridgegreys.com> napisał(a): > > On 12/03/2019 13:30, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bgolaszew...@baylibre.com> > > > > While the affected code is run in user-mode, the build still warns > > about it. Convert all uses of VLA to dynamic allocations. > > > > Signed-off-by: Bartosz Golaszewski <bgolaszew...@baylibre.com> > > --- > > arch/um/os-Linux/umid.c | 36 +++++++++++++++++++++++++++--------- > > 1 file changed, 27 insertions(+), 9 deletions(-) > > > > diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c > > index 998fbb445458..e261656fe9d7 100644 > > --- a/arch/um/os-Linux/umid.c > > +++ b/arch/um/os-Linux/umid.c > > @@ -135,12 +135,18 @@ static int remove_files_and_dir(char *dir) > > */ > > static inline int is_umdir_used(char *dir) > > { > > - char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")]; > > - char pid[sizeof("nnnnn\0")], *end; > > + char pid[sizeof("nnnnn\0")], *end, *file; > > int dead, fd, p, n, err; > > + size_t filelen; > > > > - n = snprintf(file, sizeof(file), "%s/pid", dir); > > - if (n >= sizeof(file)) { > > + err = asprintf(&file, "%s/pid", dir); > > + if (err < 0) > > + return 0; > > + > > + filelen = strlen(file); > > + > > + n = snprintf(file, filelen, "%s/pid", dir); > > + if (n >= filelen) { > > printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n"); > > err = -E2BIG; > > goto out; > > @@ -185,6 +191,7 @@ static inline int is_umdir_used(char *dir) > > out_close: > > close(fd); > > out: > > + free(file); > > return 0; > > } > > > > @@ -210,18 +217,21 @@ static int umdir_take_if_dead(char *dir) > > > > static void __init create_pid_file(void) > > { > > - char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")]; > > - char pid[sizeof("nnnnn\0")]; > > + char pid[sizeof("nnnnn\0")], *file; > > int fd, n; > > > > - if (umid_file_name("pid", file, sizeof(file))) > > + file = malloc(strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")); > > + if (!file) > > return; > > > > + if (umid_file_name("pid", file, sizeof(file))) > > + goto out; > > + > > fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644); > > if (fd < 0) { > > printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: " > > "%s\n", file, strerror(errno)); > > - return; > > + goto out; > > } > > > > snprintf(pid, sizeof(pid), "%d\n", getpid()); > > @@ -231,6 +241,8 @@ static void __init create_pid_file(void) > > errno); > > > > close(fd); > > +out: > > + free(file); > > } > > > > int __init set_umid(char *name) > > @@ -385,13 +397,19 @@ __uml_setup("uml_dir=", set_uml_dir, > > > > static void remove_umid_dir(void) > > { > > - char dir[strlen(uml_dir) + UMID_LEN + 1], err; > > + char *dir, err; > > + > > + dir = malloc(strlen(uml_dir) + UMID_LEN + 1); > > + if (!dir) > > + return; > > > > sprintf(dir, "%s%s", uml_dir, umid); > > err = remove_files_and_dir(dir); > > if (err) > > os_warn("%s - remove_files_and_dir failed with err = %d\n", > > __func__, err); > > + > > + free(dir); > > } > > > > __uml_exitcall(remove_umid_dir); > > > > Thanks for bringing it up. It helped me notice that this is actually broken. > > PID can be more than 5 digits nowdays. >
Do we have a macro in the kernel that yields the minimum size of an array to fit a number? I can't find it. I vagely remember seeing something like this in systemd tree. If it doesn't exist in the kernel then maybe we should copy it over. Bart