diff mbox series

maple_tree: Fix mas_prev() state separation code

Message ID 20231207193319.4025462-1-Liam.Howlett@oracle.com
State New
Headers
Series maple_tree: Fix mas_prev() state separation code |

Commit Message

Liam R. Howlett Dec. 7, 2023, 7:33 p.m. UTC 
  mas_prev() was setting the ma_underflow condition when the limit was
reached and not when the limit was attempting to go lower.  This
resulted in the incorrect behaviour on subsequent actions.

This commit fixes the status setting to only set ma_underflow when the
lower limit is attempted to be decremented, and modifies the testing to
ensure that's the case.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

Andrew,

This should be clean to squash into 7f79fdb1d94d7 ("maple_tree: separate
ma_state node from status.") which is currently in your mm-unstable
branch.

Thanks,
Liam


 lib/maple_tree.c      | 16 ++++++++++++----
 lib/test_maple_tree.c |  9 +++++++--
 2 files changed, 19 insertions(+), 6 deletions(-)

Comments

Kees Cook Dec. 7, 2023, 9:04 p.m. UTC | #1 
On Thu, Dec 07, 2023 at 02:33:19PM -0500, Liam R. Howlett wrote:
> mas_prev() was setting the ma_underflow condition when the limit was
> reached and not when the limit was attempting to go lower.  This
> resulted in the incorrect behaviour on subsequent actions.
> 
> This commit fixes the status setting to only set ma_underflow when the
> lower limit is attempted to be decremented, and modifies the testing to
> ensure that's the case.
> 
> Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>

Is this is related to the report[1] I forwarded? If so, please add these tags
too:

 Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
 Closes: https://lore.kernel.org/all/CA+G9fYs-j2FYZSFSVZj48mgoM9gQd4-7M2mu2Ez3D1DqDdW2bQ@mail.gmail.com/ [1]

Thanks either way!

-Kees

> ---
> 
> Andrew,
> 
> This should be clean to squash into 7f79fdb1d94d7 ("maple_tree: separate
> ma_state node from status.") which is currently in your mm-unstable
> branch.
> 
> Thanks,
> Liam
> 
> 
>  lib/maple_tree.c      | 16 ++++++++++++----
>  lib/test_maple_tree.c |  9 +++++++--
>  2 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 89f8d21602774..47f2a7a973852 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4432,6 +4432,9 @@ static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty)
>  		mas->last = mas->index - 1;
>  		mas->index = mas_safe_min(mas, pivots, mas->offset);
>  	} else  {
> +		if (mas->index <= min)
> +			goto underflow;
> +
>  		if (mas_prev_node(mas, min)) {
>  			mas_rewalk(mas, save_point);
>  			goto retry;
> @@ -4452,15 +4455,15 @@ static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty)
>  	if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
>  		goto retry;
>  
> -	if (mas->index <= min)
> -		mas->status = ma_underflow;
>  
>  	if (likely(entry))
>  		return entry;
>  
>  	if (!empty) {
> -		if (mas_is_underflow(mas))
> +		if (mas->index <= min) {
> +			mas->status = ma_underflow;
>  			return NULL;
> +		}
>  
>  		goto again;
>  	}
> @@ -4596,7 +4599,7 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty)
>  		if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
>  			goto retry;
>  
> -		if (pivot >= max) {
> +		if (pivot >= max) { /* Was at the limit, next will extend beyond */
>  			mas->status = ma_overflow;
>  			return NULL;
>  		}
> @@ -4611,6 +4614,11 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty)
>  		else
>  			mas->last = mas->max;
>  	} else  {
> +		if (mas->last >= max) {
> +			mas->status = ma_overflow;
> +			return NULL;
> +		}
> +
>  		if (mas_next_node(mas, node, max)) {
>  			mas_rewalk(mas, save_point);
>  			goto retry;
> diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
> index 15fbeb788f3ac..29185ac5c727f 100644
> --- a/lib/test_maple_tree.c
> +++ b/lib/test_maple_tree.c
> @@ -3294,8 +3294,8 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
>  	MT_BUG_ON(mt, mas.last != 0x1500);
>  	MT_BUG_ON(mt, !mas_is_active(&mas));
>  
> -	/* next:active ->active */
> -	entry = mas_next(&mas, ULONG_MAX);
> +	/* next:active ->active (spanning limit) */
> +	entry = mas_next(&mas, 0x2100);
>  	MT_BUG_ON(mt, entry != ptr2);
>  	MT_BUG_ON(mt, mas.index != 0x2000);
>  	MT_BUG_ON(mt, mas.last != 0x2500);
> @@ -3360,6 +3360,11 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
>  	MT_BUG_ON(mt, entry != ptr);
>  	MT_BUG_ON(mt, mas.index != 0x1000);
>  	MT_BUG_ON(mt, mas.last != 0x1500);
> +	MT_BUG_ON(mt, !mas_is_active(&mas)); /* spanning limit */
> +	entry = mas_prev(&mas, 0x1200); /* underflow */
> +	MT_BUG_ON(mt, entry != NULL);
> +	MT_BUG_ON(mt, mas.index != 0x1000);
> +	MT_BUG_ON(mt, mas.last != 0x1500);
>  	MT_BUG_ON(mt, !mas_is_underflow(&mas));
>  
>  	/* prev:underflow -> underflow (lower limit) spanning end range */
> -- 
> 2.40.1
>
Liam R. Howlett Dec. 8, 2023, 5:54 p.m. UTC | #2 
* Kees Cook <keescook@chromium.org> [231207 16:04]:
> On Thu, Dec 07, 2023 at 02:33:19PM -0500, Liam R. Howlett wrote:
> > mas_prev() was setting the ma_underflow condition when the limit was
> > reached and not when the limit was attempting to go lower.  This
> > resulted in the incorrect behaviour on subsequent actions.
> > 
> > This commit fixes the status setting to only set ma_underflow when the
> > lower limit is attempted to be decremented, and modifies the testing to
> > ensure that's the case.
> > 
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
> 
> Is this is related to the report[1] I forwarded? If so, please add these tags
> too:
> 
>  Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>  Closes: https://lore.kernel.org/all/CA+G9fYs-j2FYZSFSVZj48mgoM9gQd4-7M2mu2Ez3D1DqDdW2bQ@mail.gmail.com/ [1]
> 

Ah, yes it is.  I missed these tags. Sorry about that.

I have another patch to send in regards to this area on the
mmap_region() side but it's less urgent.  I'll Cc you on that one as
well.


> Thanks either way!
> 
> -Kees
> 
> > ---
> > 
> > Andrew,
> > 
> > This should be clean to squash into 7f79fdb1d94d7 ("maple_tree: separate
> > ma_state node from status.") which is currently in your mm-unstable
> > branch.
> > 
> > Thanks,
> > Liam
> > 
> > 
> >  lib/maple_tree.c      | 16 ++++++++++++----
> >  lib/test_maple_tree.c |  9 +++++++--
> >  2 files changed, 19 insertions(+), 6 deletions(-)
> > 
> > diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> > index 89f8d21602774..47f2a7a973852 100644
> > --- a/lib/maple_tree.c
> > +++ b/lib/maple_tree.c
> > @@ -4432,6 +4432,9 @@ static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty)
> >  		mas->last = mas->index - 1;
> >  		mas->index = mas_safe_min(mas, pivots, mas->offset);
> >  	} else  {
> > +		if (mas->index <= min)
> > +			goto underflow;
> > +
> >  		if (mas_prev_node(mas, min)) {
> >  			mas_rewalk(mas, save_point);
> >  			goto retry;
> > @@ -4452,15 +4455,15 @@ static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty)
> >  	if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
> >  		goto retry;
> >  
> > -	if (mas->index <= min)
> > -		mas->status = ma_underflow;
> >  
> >  	if (likely(entry))
> >  		return entry;
> >  
> >  	if (!empty) {
> > -		if (mas_is_underflow(mas))
> > +		if (mas->index <= min) {
> > +			mas->status = ma_underflow;
> >  			return NULL;
> > +		}
> >  
> >  		goto again;
> >  	}
> > @@ -4596,7 +4599,7 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty)
> >  		if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
> >  			goto retry;
> >  
> > -		if (pivot >= max) {
> > +		if (pivot >= max) { /* Was at the limit, next will extend beyond */
> >  			mas->status = ma_overflow;
> >  			return NULL;
> >  		}
> > @@ -4611,6 +4614,11 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty)
> >  		else
> >  			mas->last = mas->max;
> >  	} else  {
> > +		if (mas->last >= max) {
> > +			mas->status = ma_overflow;
> > +			return NULL;
> > +		}
> > +
> >  		if (mas_next_node(mas, node, max)) {
> >  			mas_rewalk(mas, save_point);
> >  			goto retry;
> > diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
> > index 15fbeb788f3ac..29185ac5c727f 100644
> > --- a/lib/test_maple_tree.c
> > +++ b/lib/test_maple_tree.c
> > @@ -3294,8 +3294,8 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
> >  	MT_BUG_ON(mt, mas.last != 0x1500);
> >  	MT_BUG_ON(mt, !mas_is_active(&mas));
> >  
> > -	/* next:active ->active */
> > -	entry = mas_next(&mas, ULONG_MAX);
> > +	/* next:active ->active (spanning limit) */
> > +	entry = mas_next(&mas, 0x2100);
> >  	MT_BUG_ON(mt, entry != ptr2);
> >  	MT_BUG_ON(mt, mas.index != 0x2000);
> >  	MT_BUG_ON(mt, mas.last != 0x2500);
> > @@ -3360,6 +3360,11 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
> >  	MT_BUG_ON(mt, entry != ptr);
> >  	MT_BUG_ON(mt, mas.index != 0x1000);
> >  	MT_BUG_ON(mt, mas.last != 0x1500);
> > +	MT_BUG_ON(mt, !mas_is_active(&mas)); /* spanning limit */
> > +	entry = mas_prev(&mas, 0x1200); /* underflow */
> > +	MT_BUG_ON(mt, entry != NULL);
> > +	MT_BUG_ON(mt, mas.index != 0x1000);
> > +	MT_BUG_ON(mt, mas.last != 0x1500);
> >  	MT_BUG_ON(mt, !mas_is_underflow(&mas));
> >  
> >  	/* prev:underflow -> underflow (lower limit) spanning end range */
> > -- 
> > 2.40.1
> > 
> 
> -- 
> Kees Cook
diff mbox series

Patch

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 89f8d21602774..47f2a7a973852 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4432,6 +4432,9 @@  static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty)
 		mas->last = mas->index - 1;
 		mas->index = mas_safe_min(mas, pivots, mas->offset);
 	} else  {
+		if (mas->index <= min)
+			goto underflow;
+
 		if (mas_prev_node(mas, min)) {
 			mas_rewalk(mas, save_point);
 			goto retry;
@@ -4452,15 +4455,15 @@  static void *mas_prev_slot(struct ma_state *mas, unsigned long min, bool empty)
 	if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
 		goto retry;
 
-	if (mas->index <= min)
-		mas->status = ma_underflow;
 
 	if (likely(entry))
 		return entry;
 
 	if (!empty) {
-		if (mas_is_underflow(mas))
+		if (mas->index <= min) {
+			mas->status = ma_underflow;
 			return NULL;
+		}
 
 		goto again;
 	}
@@ -4596,7 +4599,7 @@  static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty)
 		if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
 			goto retry;
 
-		if (pivot >= max) {
+		if (pivot >= max) { /* Was at the limit, next will extend beyond */
 			mas->status = ma_overflow;
 			return NULL;
 		}
@@ -4611,6 +4614,11 @@  static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty)
 		else
 			mas->last = mas->max;
 	} else  {
+		if (mas->last >= max) {
+			mas->status = ma_overflow;
+			return NULL;
+		}
+
 		if (mas_next_node(mas, node, max)) {
 			mas_rewalk(mas, save_point);
 			goto retry;
diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index 15fbeb788f3ac..29185ac5c727f 100644
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -3294,8 +3294,8 @@  static noinline void __init check_state_handling(struct maple_tree *mt)
 	MT_BUG_ON(mt, mas.last != 0x1500);
 	MT_BUG_ON(mt, !mas_is_active(&mas));
 
-	/* next:active ->active */
-	entry = mas_next(&mas, ULONG_MAX);
+	/* next:active ->active (spanning limit) */
+	entry = mas_next(&mas, 0x2100);
 	MT_BUG_ON(mt, entry != ptr2);
 	MT_BUG_ON(mt, mas.index != 0x2000);
 	MT_BUG_ON(mt, mas.last != 0x2500);
@@ -3360,6 +3360,11 @@  static noinline void __init check_state_handling(struct maple_tree *mt)
 	MT_BUG_ON(mt, entry != ptr);
 	MT_BUG_ON(mt, mas.index != 0x1000);
 	MT_BUG_ON(mt, mas.last != 0x1500);
+	MT_BUG_ON(mt, !mas_is_active(&mas)); /* spanning limit */
+	entry = mas_prev(&mas, 0x1200); /* underflow */
+	MT_BUG_ON(mt, entry != NULL);
+	MT_BUG_ON(mt, mas.index != 0x1000);
+	MT_BUG_ON(mt, mas.last != 0x1500);
 	MT_BUG_ON(mt, !mas_is_underflow(&mas));
 
 	/* prev:underflow -> underflow (lower limit) spanning end range */