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[RESEND PATCH v2] params: Annotate struct module_param_attrs with __counted_by()

Thorsten Blum posted 1 patch 11 months ago
There is a newer version of this series
kernel/params.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
[RESEND PATCH v2] params: Annotate struct module_param_attrs with __counted_by()
Posted by Thorsten Blum 11 months ago 
Add the __counted_by compiler attribute to the flexible array member
attrs to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.

Increment num before adding a new param_attribute to the attrs array and
adjust the array index accordingly. Increment num immediately after the
first reallocation such that the reallocation for the NULL terminator
only needs to add 1 (instead of 2) to mk->mp->num.

Use struct_size() instead of manually calculating the size for the
reallocation.

Use krealloc_array() for the additional NULL terminator.

Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Use krealloc_array() as suggested by Andy Shevchenko
- Link to v1: https://lore.kernel.org/r/20240823123300.37574-1-thorsten.blum@toblux.com/
---
 kernel/params.c | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/kernel/params.c b/kernel/params.c
index 2e447f8ae183..5f6643676697 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -551,7 +551,7 @@ struct module_param_attrs
 {
 	unsigned int num;
 	struct attribute_group grp;
-	struct param_attribute attrs[];
+	struct param_attribute attrs[] __counted_by(num);
 };
 
 #ifdef CONFIG_SYSFS
@@ -651,35 +651,32 @@ static __modinit int add_sysfs_param(struct module_kobject *mk,
 	}
 
 	/* Enlarge allocations. */
-	new_mp = krealloc(mk->mp,
-			  sizeof(*mk->mp) +
-			  sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
+	new_mp = krealloc(mk->mp, struct_size(mk->mp, attrs, mk->mp->num + 1),
 			  GFP_KERNEL);
 	if (!new_mp)
 		return -ENOMEM;
 	mk->mp = new_mp;
+	mk->mp->num++;
 
 	/* Extra pointer for NULL terminator */
-	new_attrs = krealloc(mk->mp->grp.attrs,
-			     sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
-			     GFP_KERNEL);
+	new_attrs = krealloc_array(mk->mp->grp.attrs, mk->mp->num + 1,
+				   sizeof(mk->mp->grp.attrs[0]), GFP_KERNEL);
 	if (!new_attrs)
 		return -ENOMEM;
 	mk->mp->grp.attrs = new_attrs;
 
 	/* Tack new one on the end. */
-	memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
-	sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
-	mk->mp->attrs[mk->mp->num].param = kp;
-	mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
+	memset(&mk->mp->attrs[mk->mp->num - 1], 0, sizeof(mk->mp->attrs[0]));
+	sysfs_attr_init(&mk->mp->attrs[mk->mp->num - 1].mattr.attr);
+	mk->mp->attrs[mk->mp->num - 1].param = kp;
+	mk->mp->attrs[mk->mp->num - 1].mattr.show = param_attr_show;
 	/* Do not allow runtime DAC changes to make param writable. */
 	if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
-		mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
+		mk->mp->attrs[mk->mp->num - 1].mattr.store = param_attr_store;
 	else
-		mk->mp->attrs[mk->mp->num].mattr.store = NULL;
-	mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
-	mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
-	mk->mp->num++;
+		mk->mp->attrs[mk->mp->num - 1].mattr.store = NULL;
+	mk->mp->attrs[mk->mp->num - 1].mattr.attr.name = (char *)name;
+	mk->mp->attrs[mk->mp->num - 1].mattr.attr.mode = kp->perm;
 
 	/* Fix up all the pointers, since krealloc can move us */
 	for (i = 0; i < mk->mp->num; i++)
-- 
2.47.1
Re: [RESEND PATCH v2] params: Annotate struct module_param_attrs with __counted_by()
Posted by Thorsten Blum 10 months, 1 week ago 
On 14. Jan 2025, at 22:49, Thorsten Blum wrote:
> Add the __counted_by compiler attribute to the flexible array member
> attrs to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
> CONFIG_FORTIFY_SOURCE.
> 
> Increment num before adding a new param_attribute to the attrs array and
> adjust the array index accordingly. Increment num immediately after the
> first reallocation such that the reallocation for the NULL terminator
> only needs to add 1 (instead of 2) to mk->mp->num.
> 
> Use struct_size() instead of manually calculating the size for the
> reallocation.
> 
> Use krealloc_array() for the additional NULL terminator.

Hi, could someone please take another look at this?

It was already applied to modules-next in August 2024, but dropped
shortly after because of a Clang issue:

https://lore.kernel.org/all/20241029140036.577804-1-kernel@jfarr.cc

The Clang issue has been fixed for a while and this patch could be
applied again.

Thanks,
Thorsten
Re: [RESEND PATCH v2] params: Annotate struct module_param_attrs with __counted_by()
Posted by Thorsten Blum 10 months ago 
On 4. Feb 2025, at 17:44, Thorsten Blum wrote:
> On 14. Jan 2025, at 22:49, Thorsten Blum wrote:
>> Add the __counted_by compiler attribute to the flexible array member
>> attrs to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
>> CONFIG_FORTIFY_SOURCE.
>> 
>> Increment num before adding a new param_attribute to the attrs array and
>> adjust the array index accordingly. Increment num immediately after the
>> first reallocation such that the reallocation for the NULL terminator
>> only needs to add 1 (instead of 2) to mk->mp->num.
>> 
>> Use struct_size() instead of manually calculating the size for the
>> reallocation.
>> 
>> Use krealloc_array() for the additional NULL terminator.
> 
> Hi, could someone please take another look at this?
> 
> It was already applied to modules-next in August 2024, but dropped
> shortly after because of a Clang issue:
> 
> https://lore.kernel.org/all/20241029140036.577804-1-kernel@jfarr.cc
> 
> The Clang issue has been fixed for a while and this patch could be
> applied again.

Hi Luis,

you already applied this to modules-next in September of last year [1].
Could you apply it again now that the Clang issue has been fixed?

Thanks,
Thorsten

[1] https://lore.kernel.org/linux-kernel/ZuHaiiMV6ESS8p7z@bombadil.infradead.org/
Re: [RESEND PATCH v2] params: Annotate struct module_param_attrs with __counted_by()
Posted by Luis Chamberlain 10 months ago 
On Tue, Feb 11, 2025 at 02:18:08PM +0100, Thorsten Blum wrote:
> On 4. Feb 2025, at 17:44, Thorsten Blum wrote:
> > On 14. Jan 2025, at 22:49, Thorsten Blum wrote:
> >> Add the __counted_by compiler attribute to the flexible array member
> >> attrs to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
> >> CONFIG_FORTIFY_SOURCE.
> >> 
> >> Increment num before adding a new param_attribute to the attrs array and
> >> adjust the array index accordingly. Increment num immediately after the
> >> first reallocation such that the reallocation for the NULL terminator
> >> only needs to add 1 (instead of 2) to mk->mp->num.
> >> 
> >> Use struct_size() instead of manually calculating the size for the
> >> reallocation.
> >> 
> >> Use krealloc_array() for the additional NULL terminator.
> > 
> > Hi, could someone please take another look at this?
> > 
> > It was already applied to modules-next in August 2024, but dropped
> > shortly after because of a Clang issue:
> > 
> > https://lore.kernel.org/all/20241029140036.577804-1-kernel@jfarr.cc
> > 
> > The Clang issue has been fixed for a while and this patch could be
> > applied again.
> 
> Hi Luis,
> 
> you already applied this to modules-next in September of last year [1].
> Could you apply it again now that the Clang issue has been fixed?

Please resend and Cc new co-maintainers, we are rotating every 6 months
so to helps scale and support Rust modules too.


  Luis
> 
> Thanks,
> Thorsten
> 
> [1] https://lore.kernel.org/linux-kernel/ZuHaiiMV6ESS8p7z@bombadil.infradead.org/

Patchew 2.1-devel-b67e4c2

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