Messages in this thread | | | Subject | Re: [PATCH] um: remove uses of variable length arrays | From | Anton Ivanov <> | Date | Thu, 14 Mar 2019 13:45:18 +0000 |
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On 14/03/2019 13:33, Bartosz Golaszewski wrote: > śr., 13 mar 2019 o 10:45 Anton Ivanov > <anton.ivanov@cambridgegreys.com> napisał(a): >> On 12/03/2019 13:30, Bartosz Golaszewski wrote: >>> From: Bartosz Golaszewski <bgolaszewski@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 <bgolaszewski@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 you want to take this patch anyway and then apply the fix for the > array on top of that or do you prefer it be fixed before that? > > Bart > I am OK to take it as is and have the PID length fixed after that.
-- Anton R. Ivanov Cambridgegreys Limited. Registered in England. Company Number 10273661 https://www.cambridgegreys.com/
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