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* [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23  7:21 ` Dan Carpenter
  0 siblings, 0 replies; 16+ messages in thread
From: Dan Carpenter @ 2018-11-23  7:21 UTC (permalink / raw)
  To: Andrew Morton, Michal Hocko
  Cc: Pavel Tatashin, Alexander Duyck, Matthew Wilcox, linux-mm,
	kernel-janitors

We had intended to only print dentry->d_name.len characters but there is
a width vs precision typo so if the name isn't NUL terminated it will
read past the end of the buffer.

Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 mm/debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/debug.c b/mm/debug.c
index d18c5cea3320..faf856b652b6 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
 		if (mapping->host->i_dentry.first) {
 			struct dentry *dentry;
 			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
-			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
+			pr_warn("name:\"%.*s\" ", dentry->d_name.len, dentry->d_name.name);
 		}
 	}
 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
-- 
2.11.0

^ permalink raw reply	[flat|nested] 16+ messages in thread

* [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23  7:21 ` Dan Carpenter
  0 siblings, 0 replies; 16+ messages in thread
From: Dan Carpenter @ 2018-11-23  7:21 UTC (permalink / raw)
  To: Andrew Morton, Michal Hocko
  Cc: Pavel Tatashin, Alexander Duyck, Matthew Wilcox, linux-mm,
	kernel-janitors

We had intended to only print dentry->d_name.len characters but there is
a width vs precision typo so if the name isn't NUL terminated it will
read past the end of the buffer.

Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 mm/debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/debug.c b/mm/debug.c
index d18c5cea3320..faf856b652b6 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
 		if (mapping->host->i_dentry.first) {
 			struct dentry *dentry;
 			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
-			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
+			pr_warn("name:\"%.*s\" ", dentry->d_name.len, dentry->d_name.name);
 		}
 	}
 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
-- 
2.11.0

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-23  7:21 ` Dan Carpenter
@ 2018-11-23  7:59   ` Anshuman Khandual
  -1 siblings, 0 replies; 16+ messages in thread
From: Anshuman Khandual @ 2018-11-23  7:47 UTC (permalink / raw)
  To: Dan Carpenter, Andrew Morton, Michal Hocko
  Cc: Pavel Tatashin, Alexander Duyck, Matthew Wilcox, linux-mm,
	kernel-janitors



On 11/23/2018 12:51 PM, Dan Carpenter wrote:
> We had intended to only print dentry->d_name.len characters but there is
> a width vs precision typo so if the name isn't NUL terminated it will
> read past the end of the buffer.
> 
> Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23  7:59   ` Anshuman Khandual
  0 siblings, 0 replies; 16+ messages in thread
From: Anshuman Khandual @ 2018-11-23  7:59 UTC (permalink / raw)
  To: Dan Carpenter, Andrew Morton, Michal Hocko
  Cc: Pavel Tatashin, Alexander Duyck, Matthew Wilcox, linux-mm,
	kernel-janitors



On 11/23/2018 12:51 PM, Dan Carpenter wrote:
> We had intended to only print dentry->d_name.len characters but there is
> a width vs precision typo so if the name isn't NUL terminated it will
> read past the end of the buffer.
> 
> Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-23  7:21 ` Dan Carpenter
@ 2018-11-23  9:01   ` Michal Hocko
  -1 siblings, 0 replies; 16+ messages in thread
From: Michal Hocko @ 2018-11-23  9:01 UTC (permalink / raw)
  To: Dan Carpenter
  Cc: Andrew Morton, Pavel Tatashin, Alexander Duyck, Matthew Wilcox,
	linux-mm, kernel-janitors

On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> We had intended to only print dentry->d_name.len characters but there is
> a width vs precision typo so if the name isn't NUL terminated it will
> read past the end of the buffer.

OK, it took me quite some time to grasp what you mean here. The code
works as expected because d_name.len and dname.name are in sync so there
no spacing going to happen. Anyway what you propose is formally more
correct I guess.
 
> Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")

This sha is an unstable sha for mmotm patch.

> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks!

> ---
>  mm/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index d18c5cea3320..faf856b652b6 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
>  		if (mapping->host->i_dentry.first) {
>  			struct dentry *dentry;
>  			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
> -			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
> +			pr_warn("name:\"%.*s\" ", dentry->d_name.len, dentry->d_name.name);
>  		}
>  	}
>  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
> -- 
> 2.11.0
> 

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23  9:01   ` Michal Hocko
  0 siblings, 0 replies; 16+ messages in thread
From: Michal Hocko @ 2018-11-23  9:01 UTC (permalink / raw)
  To: Dan Carpenter
  Cc: Andrew Morton, Pavel Tatashin, Alexander Duyck, Matthew Wilcox,
	linux-mm, kernel-janitors

On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> We had intended to only print dentry->d_name.len characters but there is
> a width vs precision typo so if the name isn't NUL terminated it will
> read past the end of the buffer.

OK, it took me quite some time to grasp what you mean here. The code
works as expected because d_name.len and dname.name are in sync so there
no spacing going to happen. Anyway what you propose is formally more
correct I guess.
 
> Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")

This sha is an unstable sha for mmotm patch.

> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks!

> ---
>  mm/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index d18c5cea3320..faf856b652b6 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
>  		if (mapping->host->i_dentry.first) {
>  			struct dentry *dentry;
>  			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
> -			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
> +			pr_warn("name:\"%.*s\" ", dentry->d_name.len, dentry->d_name.name);
>  		}
>  	}
>  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
> -- 
> 2.11.0
> 

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-23  7:21 ` Dan Carpenter
@ 2018-11-23 10:37   ` David Hildenbrand
  -1 siblings, 0 replies; 16+ messages in thread
From: David Hildenbrand @ 2018-11-23 10:37 UTC (permalink / raw)
  To: Dan Carpenter, Andrew Morton, Michal Hocko
  Cc: Pavel Tatashin, Alexander Duyck, Matthew Wilcox, linux-mm,
	kernel-janitors

On 23.11.18 08:21, Dan Carpenter wrote:
> We had intended to only print dentry->d_name.len characters but there is
> a width vs precision typo so if the name isn't NUL terminated it will
> read past the end of the buffer.
> 
> Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  mm/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index d18c5cea3320..faf856b652b6 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
>  		if (mapping->host->i_dentry.first) {
>  			struct dentry *dentry;
>  			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
> -			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
> +			pr_warn("name:\"%.*s\" ", dentry->d_name.len, dentry->d_name.name);
>  		}
>  	}
>  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23 10:37   ` David Hildenbrand
  0 siblings, 0 replies; 16+ messages in thread
From: David Hildenbrand @ 2018-11-23 10:37 UTC (permalink / raw)
  To: Dan Carpenter, Andrew Morton, Michal Hocko
  Cc: Pavel Tatashin, Alexander Duyck, Matthew Wilcox, linux-mm,
	kernel-janitors

On 23.11.18 08:21, Dan Carpenter wrote:
> We had intended to only print dentry->d_name.len characters but there is
> a width vs precision typo so if the name isn't NUL terminated it will
> read past the end of the buffer.
> 
> Fixes: 408ddbc22be3 ("mm: print more information about mapping in __dump_page")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  mm/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug.c b/mm/debug.c
> index d18c5cea3320..faf856b652b6 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
>  		if (mapping->host->i_dentry.first) {
>  			struct dentry *dentry;
>  			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
> -			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
> +			pr_warn("name:\"%.*s\" ", dentry->d_name.len, dentry->d_name.name);
>  		}
>  	}
>  	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-23  9:01   ` Michal Hocko
@ 2018-11-23 14:36     ` Dan Carpenter
  -1 siblings, 0 replies; 16+ messages in thread
From: Dan Carpenter @ 2018-11-23 14:36 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, Pavel Tatashin, Alexander Duyck, Matthew Wilcox,
	linux-mm, kernel-janitors

On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> > We had intended to only print dentry->d_name.len characters but there is
> > a width vs precision typo so if the name isn't NUL terminated it will
> > read past the end of the buffer.
> 
> OK, it took me quite some time to grasp what you mean here. The code
> works as expected because d_name.len and dname.name are in sync so there
> no spacing going to happen. Anyway what you propose is formally more
> correct I guess.
>  

Yeah.  If we are sure that the name has a NUL terminator then this
change has no effect.

regards,
dan carpenter

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23 14:36     ` Dan Carpenter
  0 siblings, 0 replies; 16+ messages in thread
From: Dan Carpenter @ 2018-11-23 14:36 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, Pavel Tatashin, Alexander Duyck, Matthew Wilcox,
	linux-mm, kernel-janitors

On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> > We had intended to only print dentry->d_name.len characters but there is
> > a width vs precision typo so if the name isn't NUL terminated it will
> > read past the end of the buffer.
> 
> OK, it took me quite some time to grasp what you mean here. The code
> works as expected because d_name.len and dname.name are in sync so there
> no spacing going to happen. Anyway what you propose is formally more
> correct I guess.
>  

Yeah.  If we are sure that the name has a NUL terminator then this
change has no effect.

regards,
dan carpenter

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-23 14:36     ` Dan Carpenter
@ 2018-11-23 14:48       ` Tetsuo Handa
  -1 siblings, 0 replies; 16+ messages in thread
From: Tetsuo Handa @ 2018-11-23 14:48 UTC (permalink / raw)
  To: Dan Carpenter, Michal Hocko
  Cc: Andrew Morton, Pavel Tatashin, Alexander Duyck, Matthew Wilcox,
	linux-mm, kernel-janitors

On 2018/11/23 23:36, Dan Carpenter wrote:
> On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
>> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
>>> We had intended to only print dentry->d_name.len characters but there is
>>> a width vs precision typo so if the name isn't NUL terminated it will
>>> read past the end of the buffer.
>>
>> OK, it took me quite some time to grasp what you mean here. The code
>> works as expected because d_name.len and dname.name are in sync so there
>> no spacing going to happen. Anyway what you propose is formally more
>> correct I guess.
>>  
> 
> Yeah.  If we are sure that the name has a NUL terminator then this
> change has no effect.

There seems to be %pd which is designed for printing "struct dentry".

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-23 14:48       ` Tetsuo Handa
  0 siblings, 0 replies; 16+ messages in thread
From: Tetsuo Handa @ 2018-11-23 14:48 UTC (permalink / raw)
  To: Dan Carpenter, Michal Hocko
  Cc: Andrew Morton, Pavel Tatashin, Alexander Duyck, Matthew Wilcox,
	linux-mm, kernel-janitors

On 2018/11/23 23:36, Dan Carpenter wrote:
> On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
>> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
>>> We had intended to only print dentry->d_name.len characters but there is
>>> a width vs precision typo so if the name isn't NUL terminated it will
>>> read past the end of the buffer.
>>
>> OK, it took me quite some time to grasp what you mean here. The code
>> works as expected because d_name.len and dname.name are in sync so there
>> no spacing going to happen. Anyway what you propose is formally more
>> correct I guess.
>>  
> 
> Yeah.  If we are sure that the name has a NUL terminator then this
> change has no effect.

There seems to be %pd which is designed for printing "struct dentry".

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-23 14:48       ` Tetsuo Handa
@ 2018-11-24  0:08         ` Andrew Morton
  -1 siblings, 0 replies; 16+ messages in thread
From: Andrew Morton @ 2018-11-24  0:08 UTC (permalink / raw)
  To: Tetsuo Handa
  Cc: Dan Carpenter, Michal Hocko, Pavel Tatashin, Alexander Duyck,
	Matthew Wilcox, linux-mm, kernel-janitors

On Fri, 23 Nov 2018 23:48:06 +0900 Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:

> On 2018/11/23 23:36, Dan Carpenter wrote:
> > On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
> >> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> >>> We had intended to only print dentry->d_name.len characters but there is
> >>> a width vs precision typo so if the name isn't NUL terminated it will
> >>> read past the end of the buffer.
> >>
> >> OK, it took me quite some time to grasp what you mean here. The code
> >> works as expected because d_name.len and dname.name are in sync so there
> >> no spacing going to happen. Anyway what you propose is formally more
> >> correct I guess.
> >>  
> > 
> > Yeah.  If we are sure that the name has a NUL terminator then this
> > change has no effect.
> 
> There seems to be %pd which is designed for printing "struct dentry".

ooh, who knew.  Can we use that please?

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-24  0:08         ` Andrew Morton
  0 siblings, 0 replies; 16+ messages in thread
From: Andrew Morton @ 2018-11-24  0:08 UTC (permalink / raw)
  To: Tetsuo Handa
  Cc: Dan Carpenter, Michal Hocko, Pavel Tatashin, Alexander Duyck,
	Matthew Wilcox, linux-mm, kernel-janitors

On Fri, 23 Nov 2018 23:48:06 +0900 Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:

> On 2018/11/23 23:36, Dan Carpenter wrote:
> > On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
> >> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> >>> We had intended to only print dentry->d_name.len characters but there is
> >>> a width vs precision typo so if the name isn't NUL terminated it will
> >>> read past the end of the buffer.
> >>
> >> OK, it took me quite some time to grasp what you mean here. The code
> >> works as expected because d_name.len and dname.name are in sync so there
> >> no spacing going to happen. Anyway what you propose is formally more
> >> correct I guess.
> >>  
> > 
> > Yeah.  If we are sure that the name has a NUL terminator then this
> > change has no effect.
> 
> There seems to be %pd which is designed for printing "struct dentry".

ooh, who knew.  Can we use that please?

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
  2018-11-24  0:08         ` Andrew Morton
@ 2018-11-25  8:08           ` Michal Hocko
  -1 siblings, 0 replies; 16+ messages in thread
From: Michal Hocko @ 2018-11-25  8:08 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Tetsuo Handa, Dan Carpenter, Pavel Tatashin, Alexander Duyck,
	Matthew Wilcox, linux-mm, kernel-janitors

On Fri 23-11-18 16:08:46, Andrew Morton wrote:
> On Fri, 23 Nov 2018 23:48:06 +0900 Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
> 
> > On 2018/11/23 23:36, Dan Carpenter wrote:
> > > On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
> > >> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> > >>> We had intended to only print dentry->d_name.len characters but there is
> > >>> a width vs precision typo so if the name isn't NUL terminated it will
> > >>> read past the end of the buffer.
> > >>
> > >> OK, it took me quite some time to grasp what you mean here. The code
> > >> works as expected because d_name.len and dname.name are in sync so there
> > >> no spacing going to happen. Anyway what you propose is formally more
> > >> correct I guess.
> > >>  
> > > 
> > > Yeah.  If we are sure that the name has a NUL terminator then this
> > > change has no effect.
> > 
> > There seems to be %pd which is designed for printing "struct dentry".
> 
> ooh, who knew.  Can we use that please?

I wasn't aware of it either. I do not mind using it instead of the
opencoded variant of mine.

This should do it, right?
diff --git a/mm/debug.c b/mm/debug.c
index d18c5cea3320..68e9a9f2df16 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
 		if (mapping->host->i_dentry.first) {
 			struct dentry *dentry;
 			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
-			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
+			pr_warn("name:\"%pd\" ", dentry);
 		}
 	}
 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 16+ messages in thread

* Re: [PATCH] mm: debug: Fix a width vs precision bug in printk
@ 2018-11-25  8:08           ` Michal Hocko
  0 siblings, 0 replies; 16+ messages in thread
From: Michal Hocko @ 2018-11-25  8:08 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Tetsuo Handa, Dan Carpenter, Pavel Tatashin, Alexander Duyck,
	Matthew Wilcox, linux-mm, kernel-janitors

On Fri 23-11-18 16:08:46, Andrew Morton wrote:
> On Fri, 23 Nov 2018 23:48:06 +0900 Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:
> 
> > On 2018/11/23 23:36, Dan Carpenter wrote:
> > > On Fri, Nov 23, 2018 at 10:01:25AM +0100, Michal Hocko wrote:
> > >> On Fri 23-11-18 10:21:35, Dan Carpenter wrote:
> > >>> We had intended to only print dentry->d_name.len characters but there is
> > >>> a width vs precision typo so if the name isn't NUL terminated it will
> > >>> read past the end of the buffer.
> > >>
> > >> OK, it took me quite some time to grasp what you mean here. The code
> > >> works as expected because d_name.len and dname.name are in sync so there
> > >> no spacing going to happen. Anyway what you propose is formally more
> > >> correct I guess.
> > >>  
> > > 
> > > Yeah.  If we are sure that the name has a NUL terminator then this
> > > change has no effect.
> > 
> > There seems to be %pd which is designed for printing "struct dentry".
> 
> ooh, who knew.  Can we use that please?

I wasn't aware of it either. I do not mind using it instead of the
opencoded variant of mine.

This should do it, right?
diff --git a/mm/debug.c b/mm/debug.c
index d18c5cea3320..68e9a9f2df16 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -80,7 +80,7 @@ void __dump_page(struct page *page, const char *reason)
 		if (mapping->host->i_dentry.first) {
 			struct dentry *dentry;
 			dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
-			pr_warn("name:\"%*s\" ", dentry->d_name.len, dentry->d_name.name);
+			pr_warn("name:\"%pd\" ", dentry);
 		}
 	}
 	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2018-11-25  8:08 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-23  7:21 [PATCH] mm: debug: Fix a width vs precision bug in printk Dan Carpenter
2018-11-23  7:21 ` Dan Carpenter
2018-11-23  7:47 ` Anshuman Khandual
2018-11-23  7:59   ` Anshuman Khandual
2018-11-23  9:01 ` Michal Hocko
2018-11-23  9:01   ` Michal Hocko
2018-11-23 14:36   ` Dan Carpenter
2018-11-23 14:36     ` Dan Carpenter
2018-11-23 14:48     ` Tetsuo Handa
2018-11-23 14:48       ` Tetsuo Handa
2018-11-24  0:08       ` Andrew Morton
2018-11-24  0:08         ` Andrew Morton
2018-11-25  8:08         ` Michal Hocko
2018-11-25  8:08           ` Michal Hocko
2018-11-23 10:37 ` David Hildenbrand
2018-11-23 10:37   ` David Hildenbrand

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