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From: Shaun Ruffell <sruffell@sruffell.net>
To: Matthias Maennich <maennich@google.com>
Cc: linux-kernel@vger.kernel.org, Martijn Coenen <maco@android.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jessica Yu <jeyu@kernel.org>
Subject: Re: [PATCH] modpost: Copy namespace string into 'struct symbol'
Date: Mon, 30 Sep 2019 16:20:46 -0500
Message-ID: <20190930212046.rhtqmnueoffe7dnr@sruffell.net> (raw)
In-Reply-To: <20190927080346.GC90796@google.com>

On Fri, Sep 27, 2019 at 09:03:46AM +0100, Matthias Maennich wrote:
> On Thu, Sep 26, 2019 at 05:24:46PM -0500, Shaun Ruffell wrote:
> > When building an out-of-tree module I was receiving many warnings from
> > modpost like:
> > 
> >  WARNING: module dahdi_vpmadt032_loader uses symbol __kmalloc from namespace ts/dahdi-linux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> >  WARNING: module dahdi_vpmadt032_loader uses symbol vpmadtreg_register from namespace linux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> >  WARNING: module dahdi_vpmadt032_loader uses symbol param_ops_int from namespace ahdi-linux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> >  WARNING: module dahdi_vpmadt032_loader uses symbol __init_waitqueue_head from namespace ux/drivers/dahdi/dahdi-version.o: ..., but does not import it.
> >  ...
> > 
> > The fundamental issue appears to be that read_dump() is passing a
> > pointer to a statically allocated buffer for the namespace which is
> > reused as the file is parsed.
> 
> Hi Shaun,
> 
> Thanks for working on this. I think you are right about the root cause
> of this. I will have a closer look at your fix later today.

Thanks Matthias.

> > @@ -672,7 +696,6 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
> > 	unsigned int crc;
> > 	enum export export;
> > 	bool is_crc = false;
> > -	const char *name, *namespace;
> > 
> > 	if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
> > 	    strstarts(symname, "__ksymtab"))
> > @@ -744,9 +767,13 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
> > 	default:
> > 		/* All exported symbols */
> > 		if (strstarts(symname, "__ksymtab_")) {
> > +			const char *name, *namespace;
> > +
> > 			name = symname + strlen("__ksymtab_");
> > 			namespace = sym_extract_namespace(&name);
> > 			sym_add_exported(name, namespace, mod, export);
> > +			if (namespace)
> > +				free((char *)name);
> 
> This probably should free namespace instead.

Given the implementation of sym_extract_namespace below, I believe
free((char *)name) is correct.

  static const char *sym_extract_namespace(const char **symname)
  {
  	size_t n;
  	char *dupsymname;
  
  	n = strcspn(*symname, ".");
  	if (n < strlen(*symname) - 1) {
  		dupsymname = NOFAIL(strdup(*symname));
  		dupsymname[n] = '\0';
  		*symname = dupsymname;
  		return dupsymname + n + 1;
  	}
  
  	return NULL;
  }

I agree that freeing name instead of namespace is a little surprising
unless you know the implementation of sym_extract_namespace.

I thought about changing the the signature of sym_extract_namespace() to
make it clear when the symname is used to return a new allocation or
not, and given your comment, perhaps I should have.

  reply index

Thread overview: 134+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-16 12:21 [PATCH 0/6] Symbol namespaces Martijn Coenen
2018-07-16 12:21 ` [PATCH 1/6] export: explicitly align struct kernel_symbol Martijn Coenen
2018-07-16 12:21 ` [PATCH 2/6] module: add support for symbol namespaces Martijn Coenen
2018-07-19 16:32   ` Jessica Yu
2018-07-20  7:54     ` Martijn Coenen
2018-07-20 14:49       ` Jessica Yu
2018-07-20 15:42         ` Martijn Coenen
2018-07-23 11:12           ` Jessica Yu
2018-07-24  7:44             ` Martijn Coenen
2018-07-24  7:56   ` Martijn Coenen
2018-07-25 15:55     ` Jessica Yu
2018-07-25 16:48       ` Lucas De Marchi
2018-07-26  7:44         ` Martijn Coenen
2018-07-16 12:21 ` [PATCH 3/6] modpost: add support for checking " Martijn Coenen
2018-07-16 12:21 ` [PATCH 4/6] modpost: add support for generating namespace dependencies Martijn Coenen
2018-07-23  6:49   ` Jessica Yu
2018-07-16 12:21 ` [PATCH 5/6] scripts: Coccinelle script for " Martijn Coenen
2018-07-16 12:21 ` [PATCH 6/6] RFC: USB: storage: move symbols into USB_STORAGE namespace Martijn Coenen
2018-07-17 15:04   ` Alan Stern
2018-07-18 13:28     ` Martijn Coenen
2018-07-16 15:33 ` [PATCH 0/6] Symbol namespaces Greg Kroah-Hartman
2018-07-23 14:28 ` Arnd Bergmann
2018-07-24  8:09   ` Martijn Coenen
2018-07-24  9:08     ` Arnd Bergmann
2019-08-13 12:16 ` [PATCH v2 0/10] Symbol namespaces - RFC Matthias Maennich
2019-08-13 12:16   ` [PATCH v2 01/10] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-13 12:40     ` Greg KH
2019-08-13 12:16   ` [PATCH v2 02/10] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-13 12:41     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 03/10] module: add support for symbol namespaces Matthias Maennich
2019-08-13 15:26     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 04/10] modpost: " Matthias Maennich
2019-08-13 15:27     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 05/10] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-13 18:17     ` Greg KH
2019-08-13 20:15     ` Saravana Kannan
2019-08-14 12:54       ` Matthias Maennich
2019-08-14 17:34         ` Saravana Kannan
2019-08-13 12:17   ` [PATCH v2 06/10] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-13 18:16     ` Greg KH
2019-08-13 18:16     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 07/10] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-13 18:21     ` Greg KH
2019-08-13 12:17   ` [PATCH v2 08/10] scripts: Coccinelle script for " Matthias Maennich
2019-08-13 12:31     ` Julia Lawall
2019-08-13 12:44     ` Greg KH
2019-08-14  6:36     ` [Cocci] " Himanshu Jha
2019-08-14  8:03       ` Matthias Maennich
2019-08-15 13:50     ` [v2 " Markus Elfring
2019-08-22  9:18       ` Matthias Maennich
2019-08-22 11:00         ` Markus Elfring
2019-08-13 12:17   ` [PATCH v2 09/10] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-13 12:42     ` Greg KH
2019-08-13 13:12       ` Greg KH
2019-08-13 12:17   ` [PATCH v2 10/10] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-13 12:45     ` Greg KH
2019-08-13 12:47     ` Greg KH
2019-08-13 15:02       ` Matthias Maennich
     [not found]   ` <20190821114955.12788-1-maennich@google.com>
2019-08-21 11:49     ` [PATCH v3 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 03/11] module: add support for symbol namespaces Matthias Maennich
2019-08-27 15:37       ` Jessica Yu
2019-08-27 16:04         ` Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 04/11] modpost: " Matthias Maennich
2019-08-26 16:21       ` Jessica Yu
2019-08-27 14:41         ` Matthias Maennich
2019-08-28  9:43           ` Jessica Yu
2019-08-28  9:55             ` Matthias Maennich
2019-08-28 10:16               ` Jessica Yu
2019-08-21 11:49     ` [PATCH v3 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-08-28 10:49       ` Jessica Yu
2019-08-28 10:56         ` Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-08-21 11:49     ` [PATCH v3 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-08-22  6:09       ` [v3 " Markus Elfring
2019-08-29 12:13       ` [PATCH v3 " Jessica Yu
2019-08-21 11:49     ` [PATCH v3 09/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-08-21 12:37       ` Greg KH
2019-08-21 13:21       ` Thomas Gleixner
2019-08-21 13:32         ` Greg KH
2019-08-21 11:49     ` [PATCH v3 10/11] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-08-21 12:38       ` Greg KH
2019-08-21 14:36         ` Jessica Yu
2019-08-21 23:13       ` Christoph Hellwig
2019-08-22  8:32         ` Matthias Maennich
2019-09-03 15:06 ` [PATCH v4 00/12] Symbol Namespaces Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 01/12] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 02/12] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 03/12] module: add support for symbol namespaces Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 04/12] modpost: " Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 05/12] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 06/12] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 07/12] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 08/12] scripts: Coccinelle script for " Matthias Maennich
2019-09-04  9:53     ` Masahiro Yamada
2019-09-05 14:46       ` Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 09/12] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-04  7:16     ` Greg KH
2019-09-03 15:06   ` [PATCH v4 10/12] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 11/12] RFC: usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-03 15:06   ` [PATCH v4 12/12] RFC: watchdog: export core symbols in WATCHDOG_CORE namespace Matthias Maennich
2019-09-03 16:10     ` Guenter Roeck
2019-09-04  8:45       ` Masahiro Yamada
2019-09-04 12:12         ` Guenter Roeck
2019-09-04 16:16           ` [usb-storage] " Matthew Dharm
2019-09-05 10:41             ` Jessica Yu
2019-09-05 10:52               ` Arnd Bergmann
2019-09-05 11:16                 ` Jessica Yu
2019-09-05 11:25                   ` Masahiro Yamada
2019-09-05 12:00                     ` Greg Kroah-Hartman
2019-09-05 11:25               ` Matthias Maennich
2019-09-04  9:37   ` [PATCH v4 00/12] Symbol Namespaces Masahiro Yamada
2019-09-06 10:32 ` [PATCH v5 00/11] " Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 01/11] module: support reading multiple values per modinfo tag Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 02/11] export: explicitly align struct kernel_symbol Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 03/11] module: add support for symbol namespaces Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 04/11] modpost: " Matthias Maennich
2019-09-26 22:24     ` [PATCH] modpost: Copy namespace string into 'struct symbol' Shaun Ruffell
2019-09-27  5:31       ` Greg Kroah-Hartman
2019-09-27  8:03       ` Matthias Maennich
2019-09-30 21:20         ` Shaun Ruffell [this message]
2019-10-01 16:19           ` Matthias Maennich
2019-10-01 19:37             ` Shaun Ruffell
2019-09-06 10:32   ` [PATCH v5 05/11] module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 06/11] export: allow definition default namespaces in Makefiles or sources Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 07/11] modpost: add support for generating namespace dependencies Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 08/11] scripts: Coccinelle script for " Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 09/11] docs: Add documentation for Symbol Namespaces Matthias Maennich
2019-09-06 10:32   ` [PATCH v5 10/11] usb-storage: remove single-use define for debugging Matthias Maennich
2019-09-06 12:59     ` Jessica Yu
2019-09-06 13:22       ` Greg KH
2019-09-06 10:32   ` [PATCH v5 11/11] usb-storage: export symbols in USB_STORAGE namespace Matthias Maennich
2019-09-09  8:35   ` [PATCH v5 00/11] Symbol Namespaces Jessica Yu

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