[PATCH][next] dm btree: Fix potential read of array with negative index i

[PATCH][next] dm btree: Fix potential read of array with negative index i

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The call to lower_bound can return -1 if the key is not found
with the bsearch, leading to a negative index access into
array node->keys[]. Ensure this cannot occur by checking for
a negative index before reading from the array.

Addresses-Coverity: ("Negative array index read")
Fixes: d69e2e7e28bd ("dm btree: improve btree residency")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/md/persistent-data/dm-btree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index b8d21b6e2953..266deaea5eea 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -1048,7 +1048,7 @@ static bool contains_key(struct btree_node *node, uint64_t key)
 {
 	int i = lower_bound(node, key);
 
-	if (le64_to_cpu(node->keys[i]) == key)
+	if (i >= 0 && le64_to_cpu(node->keys[i]) == key)
 		return true;
 
 	return false;
-- 
2.31.1

[dm-devel] [PATCH][next] dm btree: Fix potential read of array with negative index i

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The call to lower_bound can return -1 if the key is not found
with the bsearch, leading to a negative index access into
array node->keys[]. Ensure this cannot occur by checking for
a negative index before reading from the array.

Addresses-Coverity: ("Negative array index read")
Fixes: d69e2e7e28bd ("dm btree: improve btree residency")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/md/persistent-data/dm-btree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index b8d21b6e2953..266deaea5eea 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -1048,7 +1048,7 @@ static bool contains_key(struct btree_node *node, uint64_t key)
 {
 	int i = lower_bound(node, key);
 
-	if (le64_to_cpu(node->keys[i]) == key)
+	if (i >= 0 && le64_to_cpu(node->keys[i]) == key)
 		return true;
 
 	return false;
-- 
2.31.1

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Re: [dm-devel] [PATCH][next] dm btree: Fix potential read of array with negative index i

[Edward Thornber]

[-- Attachment #1.1: Type: text/plain, Size: 1202 bytes --]

ack

On Fri, May 21, 2021 at 11:52 AM Colin King <colin.king@canonical.com>
wrote:

> From: Colin Ian King <colin.king@canonical.com>
>
> The call to lower_bound can return -1 if the key is not found
> with the bsearch, leading to a negative index access into
> array node->keys[]. Ensure this cannot occur by checking for
> a negative index before reading from the array.
>
> Addresses-Coverity: ("Negative array index read")
> Fixes: d69e2e7e28bd ("dm btree: improve btree residency")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/md/persistent-data/dm-btree.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/persistent-data/dm-btree.c
> b/drivers/md/persistent-data/dm-btree.c
> index b8d21b6e2953..266deaea5eea 100644
> --- a/drivers/md/persistent-data/dm-btree.c
> +++ b/drivers/md/persistent-data/dm-btree.c
> @@ -1048,7 +1048,7 @@ static bool contains_key(struct btree_node *node,
> uint64_t key)
>  {
>         int i = lower_bound(node, key);
>
> -       if (le64_to_cpu(node->keys[i]) == key)
> +       if (i >= 0 && le64_to_cpu(node->keys[i]) == key)
>                 return true;
>
>         return false;
> --
> 2.31.1
>
>

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