From: Carlos O'Donell <carlos@redhat.com>
To: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
Peng Fan <fanpeng@loongson.cn>,
libc-alpha@sourceware.org
Cc: Xi Ruoyao <xry111@xry111.site>
Subject: Re: [PATCH] Increase judgment on buf.
Date: Fri, 19 May 2023 07:55:28 -0400 [thread overview]
Message-ID: <293741fd-f97a-0b23-6487-20253c4608fb@redhat.com> (raw)
In-Reply-To: <374d9752-5a9b-15b2-058f-62943e6c7a33@linaro.org>
On 5/19/23 07:48, Adhemerval Zanella Netto via Libc-alpha wrote:
>
>
> On 19/05/23 00:57, Peng Fan wrote:
>> When buf is empty, if it is not checked, the subsequent assignment
>> operation will trigger a page fault. This is unnecessary.
>>
>> Signed-off-by: lixing <lixing@loongson.cn>
>> Signed-off-by: Peng Fan <fanpeng@loongson.cn>
>
> The stat family is explicitly marked with nonnull for the input struct
> stat buffer, and calling with a NULL argument is an UB.
Agreed, and "Style and Conventions"
https://sourceware.org/glibc/wiki/Style_and_Conventions
says:
https://sourceware.org/glibc/wiki/Style_and_Conventions#Bugs_in_the_user_program
We should fail catastrophically and early in the case of user bugs.
The segfault generates a core dump at exactly the right point to debug the UB.
>> ---
>> sysdeps/unix/sysv/linux/fstatat64.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/sysdeps/unix/sysv/linux/fstatat64.c b/sysdeps/unix/sysv/linux/fstatat64.c
>> index 3509d3ca6d..b635a8299a 100644
>> --- a/sysdeps/unix/sysv/linux/fstatat64.c
>> +++ b/sysdeps/unix/sysv/linux/fstatat64.c
>> @@ -52,9 +52,13 @@ fstatat64_time64_statx (int fd, const char *file, struct __stat64_t64 *buf,
>> {
>> /* 32-bit kABI with default 64-bit time_t, e.g. arc, riscv32. Also
>> 64-bit time_t support is done through statx syscall. */
>> - struct statx tmp;
>> + struct statx tmp, *ptr;
>> + if (buf)
>> + ptr = &tmp;
>> + else
>> + ptr = NULL;
>> int r = INTERNAL_SYSCALL_CALL (statx, fd, file, AT_NO_AUTOMOUNT | flag,
>> - STATX_BASIC_STATS, &tmp);
>> + STATX_BASIC_STATS, ptr);
>> if (r != 0)
>> return r;
>>
>
--
Cheers,
Carlos.
next prev parent reply other threads:[~2023-05-19 11:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-19 3:57 Peng Fan
2023-05-19 11:48 ` Adhemerval Zanella Netto
2023-05-19 11:55 ` Carlos O'Donell [this message]
2023-05-20 0:29 ` lixing
[not found] <lxnjka-9sevacf455zj-1fthj246gvr4-712jsi8w59t4969pqyxmxkaq-l3n4z6dp0ybpuvpiuudtnfot-dl7onwkii2tq8gtprte6cu4fgip6f-ikuh33-a5p9ixcl44cx2h7mimcgl3xt-13bjom.1684553069255@email.android.com>
2023-05-20 10:19 ` Xi Ruoyao
2023-05-21 8:19 ` Paul Eggert
2023-05-21 8:27 ` Andreas Schwab
2023-05-21 8:44 ` Paul Eggert
2023-05-21 9:05 ` Andreas Schwab
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=293741fd-f97a-0b23-6487-20253c4608fb@redhat.com \
--to=carlos@redhat.com \
--cc=adhemerval.zanella@linaro.org \
--cc=fanpeng@loongson.cn \
--cc=libc-alpha@sourceware.org \
--cc=xry111@xry111.site \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).