[v1] Some bug fixes and cleanups related to kexec

[PATCH 1/3] kexec_file: fix incorrect end value passed to kimage_is_destination_range()

Posted by Yuntao Wang 2 years ago

The end parameter received by kimage_is_destination_range() should be the
last valid byte address of the target memory segment plus 1. However, in
the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
the corresponding value passed to kimage_is_destination_range() is the last
valid byte address of the target memory segment, which is 1 less. Fix it.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
 kernel/kexec_file.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index f9a419cd22d4..26be070d3bdd 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -435,13 +435,12 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
 		if (temp_start < start || temp_start < kbuf->buf_min)
 			return 0;
 
-		temp_end = temp_start + kbuf->memsz - 1;
-
 		/*
 		 * Make sure this does not conflict with any of existing
 		 * segments
 		 */
-		if (kimage_is_destination_range(image, temp_start, temp_end)) {
+		if (kimage_is_destination_range(image, temp_start,
+						temp_start + kbuf->memsz)) {
 			temp_start = temp_start - PAGE_SIZE;
 			continue;
 		}
@@ -475,7 +474,7 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
 		 * Make sure this does not conflict with any of existing
 		 * segments
 		 */
-		if (kimage_is_destination_range(image, temp_start, temp_end)) {
+		if (kimage_is_destination_range(image, temp_start, temp_end + 1)) {
 			temp_start = temp_start + PAGE_SIZE;
 			continue;
 		}
-- 
2.43.0

Re: [PATCH 1/3] kexec_file: fix incorrect end value passed to kimage_is_destination_range()

Posted by Eric W. Biederman 2 years ago

Yuntao Wang <ytcoode@gmail.com> writes:

> The end parameter received by kimage_is_destination_range() should be the
> last valid byte address of the target memory segment plus 1. However, in
> the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
> the corresponding value passed to kimage_is_destination_range() is the last
> valid byte address of the target memory segment, which is 1 less. Fix
> it.

If that is true we I think we should rather fix
kimage_is_destination_range.

Otherwise we run the risk of having areas whose end is not
representable, epecially on 32bit.


Eric


> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
>  kernel/kexec_file.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index f9a419cd22d4..26be070d3bdd 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -435,13 +435,12 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
>  		if (temp_start < start || temp_start < kbuf->buf_min)
>  			return 0;
>  
> -		temp_end = temp_start + kbuf->memsz - 1;
> -
>  		/*
>  		 * Make sure this does not conflict with any of existing
>  		 * segments
>  		 */
> -		if (kimage_is_destination_range(image, temp_start, temp_end)) {
> +		if (kimage_is_destination_range(image, temp_start,
> +						temp_start + kbuf->memsz)) {
>  			temp_start = temp_start - PAGE_SIZE;
>  			continue;
>  		}
> @@ -475,7 +474,7 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
>  		 * Make sure this does not conflict with any of existing
>  		 * segments
>  		 */
> -		if (kimage_is_destination_range(image, temp_start, temp_end)) {
> +		if (kimage_is_destination_range(image, temp_start, temp_end + 1)) {
>  			temp_start = temp_start + PAGE_SIZE;
>  			continue;
>  		}

Re: [PATCH 1/3] kexec_file: fix incorrect end value passed to kimage_is_destination_range()

Posted by Baoquan He 2 years ago

On 12/15/23 at 11:46am, Eric W. Biederman wrote:
> Yuntao Wang <ytcoode@gmail.com> writes:
> 
> > The end parameter received by kimage_is_destination_range() should be the
> > last valid byte address of the target memory segment plus 1. However, in
> > the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
> > the corresponding value passed to kimage_is_destination_range() is the last
> > valid byte address of the target memory segment, which is 1 less. Fix
> > it.
> 
> If that is true we I think we should rather fix
> kimage_is_destination_range.

It's true wit the current implementation of
kimage_is_destination_range(). Its callers pass the start/end+1
pair. Agree we should fix kimage_is_destination_range() instead and
adjust callers, such as kimage_alloc_normal_control_pages(), and
kimage_alloc_page().


> 
> Otherwise we run the risk of having areas whose end is not
> representable, epecially on 32bit.
> 
> 
> Eric
> 
> 
> > Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> > ---
> >  kernel/kexec_file.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> > index f9a419cd22d4..26be070d3bdd 100644
> > --- a/kernel/kexec_file.c
> > +++ b/kernel/kexec_file.c
> > @@ -435,13 +435,12 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
> >  		if (temp_start < start || temp_start < kbuf->buf_min)
> >  			return 0;
> >  
> > -		temp_end = temp_start + kbuf->memsz - 1;
> > -
> >  		/*
> >  		 * Make sure this does not conflict with any of existing
> >  		 * segments
> >  		 */
> > -		if (kimage_is_destination_range(image, temp_start, temp_end)) {
> > +		if (kimage_is_destination_range(image, temp_start,
> > +						temp_start + kbuf->memsz)) {
> >  			temp_start = temp_start - PAGE_SIZE;
> >  			continue;
> >  		}
> > @@ -475,7 +474,7 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
> >  		 * Make sure this does not conflict with any of existing
> >  		 * segments
> >  		 */
> > -		if (kimage_is_destination_range(image, temp_start, temp_end)) {
> > +		if (kimage_is_destination_range(image, temp_start, temp_end + 1)) {
> >  			temp_start = temp_start + PAGE_SIZE;
> >  			continue;
> >  		}
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
>

[PATCH 1/3 v2] kexec: modify the meaning of the end parameter in kimage_is_destination_range()

Posted by Yuntao Wang 2 years ago

The end parameter received by kimage_is_destination_range() should be the
last valid byte address of the target memory segment plus 1. However, in
the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
the corresponding value passed to kimage_is_destination_range() is the last
valid byte address of the target memory segment, which is 1 less.

There are two ways to fix this bug. We can either correct the logic of the
locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions, or we
can fix kimage_is_destination_range() by making the end parameter represent
the last valid byte address of the target memory segment. Here, we choose
the second approach.

Due to the modification to kimage_is_destination_range(), we also need to
adjust its callers, such as kimage_alloc_normal_control_pages() and
kimage_alloc_page().

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
v1->v2:
  Fix this issue using the approach suggested by Eric and Baoquan.

  As this patch is independent of the other patches in this series, I sent
  out the v2 patch separately. If it's inconvenient for anyone, I can
  resend the entire series again.

 kernel/kexec_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index be5642a4ec49..5991b3ae072c 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -276,8 +276,8 @@ int kimage_is_destination_range(struct kimage *image,
 		unsigned long mstart, mend;
 
 		mstart = image->segment[i].mem;
-		mend = mstart + image->segment[i].memsz;
-		if ((end > mstart) && (start < mend))
+		mend = mstart + image->segment[i].memsz - 1;
+		if ((end >= mstart) && (start <= mend))
 			return 1;
 	}
 
@@ -372,7 +372,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
 		addr  = pfn << PAGE_SHIFT;
 		eaddr = epfn << PAGE_SHIFT;
 		if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
-			      kimage_is_destination_range(image, addr, eaddr)) {
+			      kimage_is_destination_range(image, addr, eaddr - 1)) {
 			list_add(&pages->lru, &extra_pages);
 			pages = NULL;
 		}
@@ -716,7 +716,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
 
 		/* If the page is not a destination page use it */
 		if (!kimage_is_destination_range(image, addr,
-						  addr + PAGE_SIZE))
+						  addr + PAGE_SIZE - 1))
 			break;
 
 		/*
-- 
2.43.0

Re: [PATCH 1/3 v2] kexec: modify the meaning of the end parameter in kimage_is_destination_range()

Posted by Baoquan He 2 years ago

On 12/16/23 at 12:18pm, Yuntao Wang wrote:
> The end parameter received by kimage_is_destination_range() should be the
> last valid byte address of the target memory segment plus 1. However, in
> the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
> the corresponding value passed to kimage_is_destination_range() is the last
> valid byte address of the target memory segment, which is 1 less.
> 
> There are two ways to fix this bug. We can either correct the logic of the
> locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions, or we
> can fix kimage_is_destination_range() by making the end parameter represent
> the last valid byte address of the target memory segment. Here, we choose
> the second approach.
> 
> Due to the modification to kimage_is_destination_range(), we also need to
> adjust its callers, such as kimage_alloc_normal_control_pages() and
> kimage_alloc_page().
> 
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
> v1->v2:
>   Fix this issue using the approach suggested by Eric and Baoquan.
> 
>   As this patch is independent of the other patches in this series, I sent
>   out the v2 patch separately. If it's inconvenient for anyone, I can
>   resend the entire series again.
> 
>  kernel/kexec_core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index be5642a4ec49..5991b3ae072c 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -276,8 +276,8 @@ int kimage_is_destination_range(struct kimage *image,
>  		unsigned long mstart, mend;
>  
>  		mstart = image->segment[i].mem;
> -		mend = mstart + image->segment[i].memsz;
> -		if ((end > mstart) && (start < mend))
> +		mend = mstart + image->segment[i].memsz - 1;
> +		if ((end >= mstart) && (start <= mend))
>  			return 1;
>  	}
>  
> @@ -372,7 +372,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
>  		addr  = pfn << PAGE_SHIFT;
>  		eaddr = epfn << PAGE_SHIFT;

  		eaddr = epfn << PAGE_SHIFT - 1;

The overall looks good to me, one tiny concern is I would like to
have 'eaddr' changed as above if a specific local variable has been
defined.

>  		if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
> -			      kimage_is_destination_range(image, addr, eaddr)) {
> +			      kimage_is_destination_range(image, addr, eaddr - 1)) {

Then we have:

 +			      kimage_is_destination_range(image, addr, eaddr)) {


>  			list_add(&pages->lru, &extra_pages);
>  			pages = NULL;
>  		}
> @@ -716,7 +716,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
>  
>  		/* If the page is not a destination page use it */
>  		if (!kimage_is_destination_range(image, addr,
> -						  addr + PAGE_SIZE))
> +						  addr + PAGE_SIZE - 1))
>  			break;
>  
>  		/*
> -- 
> 2.43.0
>

[PATCH 1/3 v4] kexec: modify the meaning of the end parameter in kimage_is_destination_range()

Posted by Yuntao Wang 2 years ago

The end parameter received by kimage_is_destination_range() should be the
last valid byte address of the target memory segment plus 1. However, in
the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
the corresponding value passed to kimage_is_destination_range() is the last
valid byte address of the target memory segment, which is 1 less.

There are two ways to fix this bug. We can either correct the logic of the
locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions, or we
can fix kimage_is_destination_range() by making the end parameter represent
the last valid byte address of the target memory segment. Here, we choose
the second approach.

Due to the modification to kimage_is_destination_range(), we also need to
adjust its callers, such as kimage_alloc_normal_control_pages() and
kimage_alloc_page().

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
v1->v2:
  Fix this issue using the approach suggested by Eric and Baoquan.

  As this patch is independent of the other patches in this series, I sent
  out the v2 patch separately. If it's inconvenient for anyone, I can
  resend the entire series again.

v2->v3:
  Modify the assignment of eaddr as suggested by Baoquan.

v3->v4:
  `eaddr = epfn << PAGE_SHIFT - 1` causes a compilation warning, fix it.

 kernel/kexec_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index be5642a4ec49..e3b1a699f087 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -276,8 +276,8 @@ int kimage_is_destination_range(struct kimage *image,
 		unsigned long mstart, mend;
 
 		mstart = image->segment[i].mem;
-		mend = mstart + image->segment[i].memsz;
-		if ((end > mstart) && (start < mend))
+		mend = mstart + image->segment[i].memsz - 1;
+		if ((end >= mstart) && (start <= mend))
 			return 1;
 	}
 
@@ -370,7 +370,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
 		pfn   = page_to_boot_pfn(pages);
 		epfn  = pfn + count;
 		addr  = pfn << PAGE_SHIFT;
-		eaddr = epfn << PAGE_SHIFT;
+		eaddr = (epfn << PAGE_SHIFT) - 1;
 		if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
 			      kimage_is_destination_range(image, addr, eaddr)) {
 			list_add(&pages->lru, &extra_pages);
@@ -716,7 +716,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
 
 		/* If the page is not a destination page use it */
 		if (!kimage_is_destination_range(image, addr,
-						  addr + PAGE_SIZE))
+						  addr + PAGE_SIZE - 1))
 			break;
 
 		/*
-- 
2.43.0

Re: [PATCH 1/3 v4] kexec: modify the meaning of the end parameter in kimage_is_destination_range()

Posted by Baoquan He 2 years ago

On 12/16/23 at 08:05pm, Yuntao Wang wrote:
> The end parameter received by kimage_is_destination_range() should be the
> last valid byte address of the target memory segment plus 1. However, in
> the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
> the corresponding value passed to kimage_is_destination_range() is the last
> valid byte address of the target memory segment, which is 1 less.
> 
> There are two ways to fix this bug. We can either correct the logic of the
> locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions, or we
> can fix kimage_is_destination_range() by making the end parameter represent
> the last valid byte address of the target memory segment. Here, we choose
> the second approach.
> 
> Due to the modification to kimage_is_destination_range(), we also need to
> adjust its callers, such as kimage_alloc_normal_control_pages() and
> kimage_alloc_page().
> 
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
> v1->v2:
>   Fix this issue using the approach suggested by Eric and Baoquan.
> 
>   As this patch is independent of the other patches in this series, I sent
>   out the v2 patch separately. If it's inconvenient for anyone, I can
>   resend the entire series again.
> 
> v2->v3:
>   Modify the assignment of eaddr as suggested by Baoquan.
> 
> v3->v4:
>   `eaddr = epfn << PAGE_SHIFT - 1` causes a compilation warning, fix it.
> 
>  kernel/kexec_core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

The whole series looks good to me with this v4 of patch 1, you may need
to reorganize them and repost.

Acked-by: Baoquan He <bhe@redhat.com>

> 
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index be5642a4ec49..e3b1a699f087 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -276,8 +276,8 @@ int kimage_is_destination_range(struct kimage *image,
>  		unsigned long mstart, mend;
>  
>  		mstart = image->segment[i].mem;
> -		mend = mstart + image->segment[i].memsz;
> -		if ((end > mstart) && (start < mend))
> +		mend = mstart + image->segment[i].memsz - 1;
> +		if ((end >= mstart) && (start <= mend))
>  			return 1;
>  	}
>  
> @@ -370,7 +370,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
>  		pfn   = page_to_boot_pfn(pages);
>  		epfn  = pfn + count;
>  		addr  = pfn << PAGE_SHIFT;
> -		eaddr = epfn << PAGE_SHIFT;
> +		eaddr = (epfn << PAGE_SHIFT) - 1;
>  		if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
>  			      kimage_is_destination_range(image, addr, eaddr)) {
>  			list_add(&pages->lru, &extra_pages);
> @@ -716,7 +716,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
>  
>  		/* If the page is not a destination page use it */
>  		if (!kimage_is_destination_range(image, addr,
> -						  addr + PAGE_SIZE))
> +						  addr + PAGE_SIZE - 1))
>  			break;
>  
>  		/*
> -- 
> 2.43.0
>

[PATCH 1/3 v3] kexec: modify the meaning of the end parameter in kimage_is_destination_range()

Posted by Yuntao Wang 2 years ago

The end parameter received by kimage_is_destination_range() should be the
last valid byte address of the target memory segment plus 1. However, in
the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
the corresponding value passed to kimage_is_destination_range() is the last
valid byte address of the target memory segment, which is 1 less.

There are two ways to fix this bug. We can either correct the logic of the
locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions, or we
can fix kimage_is_destination_range() by making the end parameter represent
the last valid byte address of the target memory segment. Here, we choose
the second approach.

Due to the modification to kimage_is_destination_range(), we also need to
adjust its callers, such as kimage_alloc_normal_control_pages() and
kimage_alloc_page().

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
v1->v2:
  Fix this issue using the approach suggested by Eric and Baoquan.

  As this patch is independent of the other patches in this series, I sent
  out the v2 patch separately. If it's inconvenient for anyone, I can
  resend the entire series again.

v2->v3:
  Modify the assignment of eaddr as suggested by Baoquan.

 kernel/kexec_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index be5642a4ec49..e65e8f186eff 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -276,8 +276,8 @@ int kimage_is_destination_range(struct kimage *image,
 		unsigned long mstart, mend;
 
 		mstart = image->segment[i].mem;
-		mend = mstart + image->segment[i].memsz;
-		if ((end > mstart) && (start < mend))
+		mend = mstart + image->segment[i].memsz - 1;
+		if ((end >= mstart) && (start <= mend))
 			return 1;
 	}
 
@@ -370,7 +370,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
 		pfn   = page_to_boot_pfn(pages);
 		epfn  = pfn + count;
 		addr  = pfn << PAGE_SHIFT;
-		eaddr = epfn << PAGE_SHIFT;
+		eaddr = epfn << PAGE_SHIFT - 1;
 		if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
 			      kimage_is_destination_range(image, addr, eaddr)) {
 			list_add(&pages->lru, &extra_pages);
@@ -716,7 +716,7 @@ static struct page *kimage_alloc_page(struct kimage *image,
 
 		/* If the page is not a destination page use it */
 		if (!kimage_is_destination_range(image, addr,
-						  addr + PAGE_SIZE))
+						  addr + PAGE_SIZE - 1))
 			break;
 
 		/*
-- 
2.43.0