LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jessica Yu <jeyu@kernel.org>
To: Thomas Richter <tmricht@linux.ibm.com>
Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
	borntraeger@de.ibm.com, schwidefsky@de.ibm.com,
	brueckner@linux.vnet.ibm.com, heiko.carstens@de.ibm.com,
	peterz@infradead.org, acme@kernel.org, me@tobin.cc,
	keescook@chromium.org, stable@vger.kernel.org
Subject: Re: [PATCH v3] module: Fix display of wrong  module .text address
Date: Wed, 18 Apr 2018 15:21:38 +0200	[thread overview]
Message-ID: <20180418132138.4xzgnwi6k3uojghv@redbean> (raw)
In-Reply-To: <20180418071436.21392-1-tmricht@linux.ibm.com>

+++ Thomas Richter [18/04/18 09:14 +0200]:
>Reading file /proc/modules shows the correct address:
>[root@s35lp76 ~]# cat /proc/modules | egrep '^qeth_l2'
>qeth_l2 94208 1 - Live 0x000003ff80401000
>
>and reading file /sys/module/qeth_l2/sections/.text
>[root@s35lp76 ~]# cat /sys/module/qeth_l2/sections/.text
>0x0000000018ea8363
>displays a random address.
>
>This breaks the perf tool which uses this address on s390
>to calculate start of .text section in memory.
>
>Fix this by printing the correct (unhashed) address.
>
>Thanks to Jessica Yu for helping on this.
>
>Fixes: ef0010a30935 ("vsprintf: don't use 'restricted_pointer()' when not restricting")
>Cc: <stable@vger.kernel.org> # v4.15+
>Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
>Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
>Cc: Jessica Yu <jeyu@kernel.org>

Thanks for turning this into a real patch. Looks good to me, if Linus
wants to take it directly:

Acked-by: Jessica Yu <jeyu@kernel.org>

Otherwise I can take this up my tree.

As Linus mentioned, we should technically be checking the opening
task's credentials/capabilities, but converting everything to pass the
actual struct seq_file/file to the sysfs show handlers would be fairly
painful :/ At least those /sys/module/*/sections/ files are all set to
0400. I think this fix is sufficient for now.

>---
> kernel/module.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
>diff --git a/kernel/module.c b/kernel/module.c
>index a6e43a5806a1..40b42000bd80 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -1472,7 +1472,8 @@ static ssize_t module_sect_show(struct module_attribute *mattr,
> {
> 	struct module_sect_attr *sattr =
> 		container_of(mattr, struct module_sect_attr, mattr);
>-	return sprintf(buf, "0x%pK\n", (void *)sattr->address);
>+	return sprintf(buf, "0x%px\n", kptr_restrict < 2 ?
>+		       (void *)sattr->address : NULL);
> }
>
> static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
>-- 
>2.14.3
>

  parent reply	other threads:[~2018-04-18 13:21 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-18  7:14 Thomas Richter
2018-04-18  7:17 ` Tobin C. Harding
2018-04-18  7:22   ` Thomas-Mich Richter
2018-04-18 13:21 ` Jessica Yu [this message]
2018-04-18 18:09   ` Linus Torvalds
2018-05-02  2:20 ` Kees Cook
2018-05-02  8:13   ` Thomas-Mich Richter
2018-05-02 14:20     ` Kees Cook

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=20180418132138.4xzgnwi6k3uojghv@redbean \
    --to=jeyu@kernel.org \
    --cc=acme@kernel.org \
    --cc=borntraeger@de.ibm.com \
    --cc=brueckner@linux.vnet.ibm.com \
    --cc=heiko.carstens@de.ibm.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=me@tobin.cc \
    --cc=peterz@infradead.org \
    --cc=schwidefsky@de.ibm.com \
    --cc=stable@vger.kernel.org \
    --cc=tmricht@linux.ibm.com \
    --cc=torvalds@linux-foundation.org \
    --subject='Re: [PATCH v3] module: Fix display of wrong  module .text address' \
    /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

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 NNTP newsgroup(s).