Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <CAN30aBEYa12Be748n_AD04B9XpZTWJCY8SvR5cx+_sz4ceT+bA@mail.gmail.com>
Date: Tue, 12 Jan 2021 00:58:05 -0800
From: Fangrui Song <emacsray@...il.com>
To: musl@...ts.openwall.com
Cc: Zengweilin <zengweilin@...wei.com>, "liucheng (G)" <liucheng32@...wei.com>, 
	"chenzefeng (A)" <chenzefeng2@...wei.com>
Subject: Re: [PATCH] fix segfault in getitimer when old argument is NULL

On Mon, Jan 11, 2021 at 11:57 PM zhuyan (M) <zhuyan34@...wei.com> wrote:
>
>
> When old is NULL, call old->it_interval.tv_sec to dereference a null pointer in getitimer.
>
> The commit 558c01338b0b635632e70af6ec8a484ca70b0328 introduces this problem.
>
> Signed-off-by: Qing Wu <wuqing30@...wei.com>
> Signed-off-by: Yan Zhu <zhuyan34@...wei.com>
> ---
>  src/signal/getitimer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/signal/getitimer.c b/src/signal/getitimer.c index 36d1eb9d..f6fde204 100644
> --- a/src/signal/getitimer.c
> +++ b/src/signal/getitimer.c
> @@ -6,7 +6,7 @@ int getitimer(int which, struct itimerval *old)
>         if (sizeof(time_t) > sizeof(long)) {
>                 long old32[4];
>                 int r = __syscall(SYS_getitimer, which, old32);
> -               if (!r) {
> +               if (!r && old) {
>                         old->it_interval.tv_sec = old32[0];
>                         old->it_interval.tv_usec = old32[1];
>                         old->it_value.tv_sec = old32[2];
> --
> 2.12.3
>

Null old is not sensible. POSIX and the Linux manpage say "The
getitimer() function shall store the current value of the timer
specified by which into the structure pointed to by value."
NULL is not a valid structure. musl does not need to work around
application bugs.

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.