| Message ID | 20210722191529.11013-1-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [next] net: dsa: sja1105: remove redundant re-assignment of pointer table | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 7 of 7 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
On Thu, Jul 22, 2021 at 08:15:29PM +0100, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > The pointer table is being re-assigned with a value that is never > read. The assignment is redundant and can be removed. > > Addresses-Coverity: ("Unused value") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > drivers/net/dsa/sja1105/sja1105_main.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c > index 6618abba23b3..c65dba3111d7 100644 > --- a/drivers/net/dsa/sja1105/sja1105_main.c > +++ b/drivers/net/dsa/sja1105/sja1105_main.c > @@ -2157,8 +2157,6 @@ static int sja1105_build_vlan_table(struct sja1105_private *priv) > if (!new_vlan) > return -ENOMEM; > > - table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP]; > - > for (i = 0; i < VLAN_N_VID; i++) > new_vlan[i].vlanid = VLAN_N_VID; > > -- > 2.31.1 > Oh my, what an interesting bug you uncovered. That duplicate assignment was introduced in commit 3f01c91aab92 ("net: dsa: sja1105: implement VLAN retagging for dsa_8021q sub-VLANs") and used to read: table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP]; new_retagging = kcalloc(SJA1105_MAX_RETAGGING_COUNT, table->ops->unpacked_entry_size, GFP_KERNEL); In retrospect, it should have been: table = &priv->static_config.tables[BLK_IDX_RETAGGING]; because we must allocate SJA1105_MAX_RETAGGING_COUNT elements of the size of one VLAN retagging entry, and not of one VLAN lookup entry. In commit 0fac6aa098ed ("net: dsa: sja1105: delete the best_effort_vlan_filtering mode") I deleted everything that had to do with VLAN retagging but left this behind because it didn't say RETAGGING on it. [BLK_IDX_VLAN_LOOKUP] = { .unpacked_entry_size = sizeof(struct sja1105_vlan_lookup_entry), }, [BLK_IDX_RETAGGING] = { .unpacked_entry_size = sizeof(struct sja1105_retagging_entry), }, and if you look at them, struct sja1105_retagging_entry has 7 u64 fields, while struct sja1105_vlan_lookup_entry has 6 elements (actually since commit 3e77e59bf8cf ("net: dsa: sja1105: add support for the SJA1110 switch family") it also has 7. The point is, between commit 3f01c91aab92 and commit 3e77e59bf8cf, the driver allocated 8 bytes too few per VLAN retagging entry, or multiplied by 32 (the value of SJA1105_MAX_RETAGGING_COUNT), it only allocates enough memory for 27.4 VLAN retagging entries. So any attempt to access VLAN retagging entries 27-31 in this function would trigger an out of bounds memory access. Could you please also send a patch for the "net" tree with this, and the explanation above? - table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP]; + table = &priv->static_config.tables[BLK_IDX_RETAGGING]; Thanks.
On Thu, Jul 22, 2021 at 11:05:44PM +0300, Vladimir Oltean wrote: > Could you please also send a patch for the "net" tree with this, and the > explanation above? > > - table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP]; > + table = &priv->static_config.tables[BLK_IDX_RETAGGING]; I think it's best for me to just send that patch. I will send it towards the "stable" trees directly, to avoid all sorts of conflicts with "net" and "net-next" (as mentioned, the VLAN retagging code is going away). For this patch towards net-next: Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c index 6618abba23b3..c65dba3111d7 100644 --- a/drivers/net/dsa/sja1105/sja1105_main.c +++ b/drivers/net/dsa/sja1105/sja1105_main.c @@ -2157,8 +2157,6 @@ static int sja1105_build_vlan_table(struct sja1105_private *priv) if (!new_vlan) return -ENOMEM; - table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP]; - for (i = 0; i < VLAN_N_VID; i++) new_vlan[i].vlanid = VLAN_N_VID;