2021-07-12 12:16:30

by Colin King

Subject: [PATCH] 6lowpan: iphc: Fix an off-by-one check of array index

From: Colin Ian King <[email protected]>

The bounds check of id is off-by-one and the comparison should
be >= rather >. Currently the WARN_ON_ONCE check does not stop
the out of range indexing of &ldev->ctx.table[id] so also add
a return path if the bounds are out of range.

Addresses-Coverity: ("Illegal address computation").
Fixes: 5609c185f24d ("6lowpan: iphc: add support for stateful compression")
Signed-off-by: Colin Ian King <[email protected]>
---
net/6lowpan/debugfs.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/6lowpan/debugfs.c b/net/6lowpan/debugfs.c
index 1c140af06d52..600b9563bfc5 100644
--- a/net/6lowpan/debugfs.c
+++ b/net/6lowpan/debugfs.c
@@ -170,7 +170,8 @@ static void lowpan_dev_debugfs_ctx_init(struct net_device *dev,
struct dentry *root;
char buf[32];

- WARN_ON_ONCE(id > LOWPAN_IPHC_CTX_TABLE_SIZE);
+ if (WARN_ON_ONCE(id >= LOWPAN_IPHC_CTX_TABLE_SIZE))
+ return;

sprintf(buf, "%d", id);

--
2.31.1

2021-07-22 14:22:37

by Marcel Holtmann

Subject: Re: [PATCH] 6lowpan: iphc: Fix an off-by-one check of array index

Hi Colin,

> The bounds check of id is off-by-one and the comparison should
> be >= rather >. Currently the WARN_ON_ONCE check does not stop
> the out of range indexing of &ldev->ctx.table[id] so also add
> a return path if the bounds are out of range.
>
> Addresses-Coverity: ("Illegal address computation").
> Fixes: 5609c185f24d ("6lowpan: iphc: add support for stateful compression")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> net/6lowpan/debugfs.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel