Re: [PATCH] coredump: fix cn_printf formatting warnings

From: Nicolas Iooss
Date: Mon Mar 16 2015 - 08:24:04 EST


Ping? Comments (or NACK or ACK) would be greatly appreciated on this
patch. Of course, if you prefer to use init_user_ns instead of
cred->user_ns, I can send an other patch.

Nicolas

On 03/06/2015 09:00 PM, Nicolas Iooss wrote:
> Add __printf attributes to cn_*printf functions. With these, gcc says:
>
> fs/coredump.c:213:5: warning: format '%d' expects argument of type
> 'int', but argument 3 has type 'kuid_t' [-Wformat=]
> err = cn_printf(cn, "%d", cred->uid);
> ^
> fs/coredump.c:217:5: warning: format '%d' expects argument of type
> 'int', but argument 3 has type 'kgid_t' [-Wformat=]
> err = cn_printf(cn, "%d", cred->gid);
> ^
> fs/coredump.c:225:5: warning: format '%ld' expects argument of type
> 'long int', but argument 3 has type 'int' [-Wformat=]
> err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
> ^
>
> The third warning is easily fixed as si_signo is always an int.
>
> For the two others, cred->uid and cred->gid need to be converted to
> either a user-namespace UID/GID or to init_user_ns UID/GID. As
> Documentation/sysctl/kernel.txt does not specify which user namespace is
> used to translate %u and %g in core_pattern, but lowercase %p and %i are
> used to format pid/tid in current process namespace, it seems intuitive
> that lowercase %u and %g use the current user namespace. So implement
> this.
>
> Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
> ---
> fs/coredump.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/fs/coredump.c b/fs/coredump.c
> index f319926ddf8c..762d827825a8 100644
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -70,7 +70,8 @@ static int expand_corename(struct core_name *cn, int size)
> return 0;
> }
>
> -static int cn_vprintf(struct core_name *cn, const char *fmt, va_list arg)
> +static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt,
> + va_list arg)
> {
> int free, need;
> va_list arg_copy;
> @@ -93,7 +94,7 @@ again:
> return -ENOMEM;
> }
>
> -static int cn_printf(struct core_name *cn, const char *fmt, ...)
> +static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...)
> {
> va_list arg;
> int ret;
> @@ -105,7 +106,8 @@ static int cn_printf(struct core_name *cn, const char *fmt, ...)
> return ret;
> }
>
> -static int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
> +static __printf(2, 3)
> +int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
> {
> int cur = cn->used;
> va_list arg;
> @@ -209,11 +211,15 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm)
> break;
> /* uid */
> case 'u':
> - err = cn_printf(cn, "%d", cred->uid);
> + err = cn_printf(cn, "%d",
> + from_kuid_munged(cred->user_ns,
> + cred->uid));
> break;
> /* gid */
> case 'g':
> - err = cn_printf(cn, "%d", cred->gid);
> + err = cn_printf(cn, "%d",
> + from_kgid_munged(cred->user_ns,
> + cred->gid));
> break;
> case 'd':
> err = cn_printf(cn, "%d",
> @@ -221,7 +227,7 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm)
> break;
> /* signal that caused the coredump */
> case 's':
> - err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
> + err = cn_printf(cn, "%d", cprm->siginfo->si_signo);
> break;
> /* UNIX time of coredump */
> case 't': {
>
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