[PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[Daniil Dulov]

The max length of volume->vid value is 20 characters.
So increase idbuf[] size up to 20 to avoid overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
---
 fs/afs/volume.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 020ecd45e476..d4a379bfd54e 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -353,7 +353,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 {
 	struct afs_server_list *new, *old, *discard;
 	struct afs_vldb_entry *vldb;
-	char idbuf[16];
+	char idbuf[20];
 	int ret, idsz;
 
 	_enter("");
-- 
2.25.1

Re: [PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[Jeffrey E Altman]

On 2/12/2024 3:33 AM, Daniil Dulov wrote:
> The max length of volume->vid value is 20 characters.
> So increase idbuf[] size up to 20 to avoid overflow.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
> Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
> ---
>   fs/afs/volume.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/afs/volume.c b/fs/afs/volume.c
> index 020ecd45e476..d4a379bfd54e 100644
> --- a/fs/afs/volume.c
> +++ b/fs/afs/volume.c
> @@ -353,7 +353,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
>   {
>   	struct afs_server_list *new, *old, *discard;
>   	struct afs_vldb_entry *vldb;
> -	char idbuf[16];
> +	char idbuf[20];
>   	int ret, idsz;
>   
>   	_enter("");

Reviewed-by: Jeffrey Altman <jaltman@auristor.com>

Re: [PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[David Howells]

Daniil Dulov <d.dulov@aladdin.ru> wrote:

> The max length of volume->vid value is 20 characters.
> So increase idbuf[] size up to 20 to avoid overflow.

Is that 20 including the NUL?  If not, I'd increase it to 24 (it's likely to
get rounded up to a multiple of 4 or 8 by the compiler).

David

Re: [PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[David Howells]

I suggest the attached instead.

David
---
diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 020ecd45e476..af3a3f57c1b3 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -353,7 +353,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 {
 	struct afs_server_list *new, *old, *discard;
 	struct afs_vldb_entry *vldb;
-	char idbuf[16];
+	char idbuf[24];
 	int ret, idsz;
 
 	_enter("");
@@ -361,7 +361,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 	/* We look up an ID by passing it as a decimal string in the
 	 * operation's name parameter.
 	 */
-	idsz = sprintf(idbuf, "%llu", volume->vid);
+	idsz = snprintf(idbuf, sizeof(idbuf), "%llu", volume->vid);
 
 	vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
 	if (IS_ERR(vldb)) {

RE: [PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[Daniil Dulov]

Hello!

Thank you for your feedback. I agree with the suggested improvement. I will send v3 a bit later today.

-----Original Message-----
From: David Howells [mailto:dhowells@redhat.com] 
Sent: Monday, February 19, 2024 1:34 PM
To: Daniil Dulov <D.Dulov@aladdin.ru>
Cc: dhowells@redhat.com; Jeffrey E Altman <jaltman@auristor.com>; linux-afs@lists.infradead.org; Marc Dionne <marc.dionne@auristor.com>; linux-kernel@vger.kernel.org; lvc-project@linuxtesting.org
Subject: Re: [PATCH v2] afs: Increase buffer size in afs_update_volume_status()

I suggest the attached instead.

David
---
diff --git a/fs/afs/volume.c b/fs/afs/volume.c index 020ecd45e476..af3a3f57c1b3 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -353,7 +353,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)  {
 	struct afs_server_list *new, *old, *discard;
 	struct afs_vldb_entry *vldb;
-	char idbuf[16];
+	char idbuf[24];
 	int ret, idsz;
 
 	_enter("");
@@ -361,7 +361,7 @@ static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
 	/* We look up an ID by passing it as a decimal string in the
 	 * operation's name parameter.
 	 */
-	idsz = sprintf(idbuf, "%llu", volume->vid);
+	idsz = snprintf(idbuf, sizeof(idbuf), "%llu", volume->vid);
 
 	vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
 	if (IS_ERR(vldb)) {

Re: [PATCH v2] afs: Increase buffer size in afs_update_volume_status()

[David Howells]

Daniil Dulov <D.Dulov@aladdin.ru> wrote:

> Thank you for your feedback. I agree with the suggested improvement. I will send v3 a bit later today.

I posted an updated patch:

https://lore.kernel.org/linux-fsdevel/20240219143906.138346-3-dhowells@redhat.com/T/#u