diff mbox series

[net,v2] rtnetlink: fix error logic of IFLA_BRIDGE_FLAGS writing back

Message ID 20240227121128.608110-1-linma@zju.edu.cn (mailing list archive)
State Accepted
Commit 743ad091fb46e622f1b690385bb15e3cd3daf874
Delegated to: Netdev Maintainers
Headers show
Series [net,v2] rtnetlink: fix error logic of IFLA_BRIDGE_FLAGS writing back | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 958 this patch: 958
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 8 of 8 maintainers
netdev/build_clang success Errors and warnings before: 974 this patch: 974
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 975 this patch: 975
netdev/checkpatch warning WARNING: line length of 84 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-02-27--15-00 (tests: 1452)

Commit Message

Lin Ma Feb. 27, 2024, 12:11 p.m. UTC
In the commit d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks
IFLA_BRIDGE_MODE length"), an adjustment was made to the old loop logic
in the function `rtnl_bridge_setlink` to enable the loop to also check
the length of the IFLA_BRIDGE_MODE attribute. However, this adjustment
removed the `break` statement and led to an error logic of the flags
writing back at the end of this function.

if (have_flags)
    memcpy(nla_data(attr), &flags, sizeof(flags));
    // attr should point to IFLA_BRIDGE_FLAGS NLA !!!

Before the mentioned commit, the `attr` is granted to be IFLA_BRIDGE_FLAGS.
However, this is not necessarily true fow now as the updated loop will let
the attr point to the last NLA, even an invalid NLA which could cause
overflow writes.

This patch introduces a new variable `br_flag` to save the NLA pointer
that points to IFLA_BRIDGE_FLAGS and uses it to resolve the mentioned
error logic.

Fixes: d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
---
v1 -> v2: rename the br_flag to br_flags_attr which offers better
          description suggested by Nikolay.

 net/core/rtnetlink.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Comments

Jiri Pirko Feb. 27, 2024, 12:31 p.m. UTC | #1
Tue, Feb 27, 2024 at 01:11:28PM CET, linma@zju.edu.cn wrote:
>In the commit d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks
>IFLA_BRIDGE_MODE length"), an adjustment was made to the old loop logic
>in the function `rtnl_bridge_setlink` to enable the loop to also check
>the length of the IFLA_BRIDGE_MODE attribute. However, this adjustment
>removed the `break` statement and led to an error logic of the flags
>writing back at the end of this function.
>
>if (have_flags)
>    memcpy(nla_data(attr), &flags, sizeof(flags));
>    // attr should point to IFLA_BRIDGE_FLAGS NLA !!!
>
>Before the mentioned commit, the `attr` is granted to be IFLA_BRIDGE_FLAGS.
>However, this is not necessarily true fow now as the updated loop will let
>the attr point to the last NLA, even an invalid NLA which could cause
>overflow writes.
>
>This patch introduces a new variable `br_flag` to save the NLA pointer
>that points to IFLA_BRIDGE_FLAGS and uses it to resolve the mentioned
>error logic.
>
>Fixes: d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length")
>Signed-off-by: Lin Ma <linma@zju.edu.cn>
>---
>v1 -> v2: rename the br_flag to br_flags_attr which offers better
>          description suggested by Nikolay.

https://www.kernel.org/doc/html/v6.6/process/maintainer-netdev.html?highlight=network#tl-dr

"don't repost your patches within one 24h period"
Lin Ma Feb. 27, 2024, 12:38 p.m. UTC | #2
> 
> https://www.kernel.org/doc/html/v6.6/process/maintainer-netdev.html?highlight=network#tl-dr
> 
> "don't repost your patches within one 24h period"

Apologize for this mistake, and I promise to be more careful
in the future. Thank you for bringing this to my attention

Regards
Lin
Nikolay Aleksandrov Feb. 27, 2024, 12:48 p.m. UTC | #3
On 2/27/24 14:11, Lin Ma wrote:
> In the commit d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks
> IFLA_BRIDGE_MODE length"), an adjustment was made to the old loop logic
> in the function `rtnl_bridge_setlink` to enable the loop to also check
> the length of the IFLA_BRIDGE_MODE attribute. However, this adjustment
> removed the `break` statement and led to an error logic of the flags
> writing back at the end of this function.
> 
> if (have_flags)
>      memcpy(nla_data(attr), &flags, sizeof(flags));
>      // attr should point to IFLA_BRIDGE_FLAGS NLA !!!
> 
> Before the mentioned commit, the `attr` is granted to be IFLA_BRIDGE_FLAGS.
> However, this is not necessarily true fow now as the updated loop will let
> the attr point to the last NLA, even an invalid NLA which could cause
> overflow writes.
> 
> This patch introduces a new variable `br_flag` to save the NLA pointer
> that points to IFLA_BRIDGE_FLAGS and uses it to resolve the mentioned
> error logic.
> 
> Fixes: d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length")
> Signed-off-by: Lin Ma <linma@zju.edu.cn>
> ---
> v1 -> v2: rename the br_flag to br_flags_attr which offers better
>            description suggested by Nikolay.
> 
>   net/core/rtnetlink.c | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)
> 

As Jiri pointed out, you should wait a day before posting another
version. The patch itself looks good to me:

Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
patchwork-bot+netdevbpf@kernel.org Feb. 29, 2024, 3:50 a.m. UTC | #4
Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 27 Feb 2024 20:11:28 +0800 you wrote:
> In the commit d73ef2d69c0d ("rtnetlink: let rtnl_bridge_setlink checks
> IFLA_BRIDGE_MODE length"), an adjustment was made to the old loop logic
> in the function `rtnl_bridge_setlink` to enable the loop to also check
> the length of the IFLA_BRIDGE_MODE attribute. However, this adjustment
> removed the `break` statement and led to an error logic of the flags
> writing back at the end of this function.
> 
> [...]

Here is the summary with links:
  - [net,v2] rtnetlink: fix error logic of IFLA_BRIDGE_FLAGS writing back
    https://git.kernel.org/netdev/net/c/743ad091fb46

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 9c4f427f3a50..ae86f751efc3 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -5169,10 +5169,9 @@  static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct net *net = sock_net(skb->sk);
 	struct ifinfomsg *ifm;
 	struct net_device *dev;
-	struct nlattr *br_spec, *attr = NULL;
+	struct nlattr *br_spec, *attr, *br_flags_attr = NULL;
 	int rem, err = -EOPNOTSUPP;
 	u16 flags = 0;
-	bool have_flags = false;
 
 	if (nlmsg_len(nlh) < sizeof(*ifm))
 		return -EINVAL;
@@ -5190,11 +5189,11 @@  static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
 	if (br_spec) {
 		nla_for_each_nested(attr, br_spec, rem) {
-			if (nla_type(attr) == IFLA_BRIDGE_FLAGS && !have_flags) {
+			if (nla_type(attr) == IFLA_BRIDGE_FLAGS && !br_flags_attr) {
 				if (nla_len(attr) < sizeof(flags))
 					return -EINVAL;
 
-				have_flags = true;
+				br_flags_attr = attr;
 				flags = nla_get_u16(attr);
 			}
 
@@ -5238,8 +5237,8 @@  static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		}
 	}
 
-	if (have_flags)
-		memcpy(nla_data(attr), &flags, sizeof(flags));
+	if (br_flags_attr)
+		memcpy(nla_data(br_flags_attr), &flags, sizeof(flags));
 out:
 	return err;
 }