| Message ID | 20240826140628.99849-1-djahchankoike@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next,v2] net: ethtool: fix unheld rtnl lock | expand |
Hi, Thanks for addressing this. I do have some comments though : On Mon, 26 Aug 2024 11:06:13 -0300 Diogo Jahchan Koike <djahchankoike@gmail.com> wrote: > ethnl_req_get_phydev should be called with rtnl lock held. > > Reported-by: syzbot+ec369e6d58e210135f71@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=ec369e6d58e210135f71 > Fixes: 31748765bed3 ("net: ethtool: pse-pd: Target the command to the requested PHY") > Signed-off-by: Diogo Jahchan Koike <djahchankoike@gmail.com> > --- > net/ethtool/pse-pd.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/ethtool/pse-pd.c b/net/ethtool/pse-pd.c > index 507cb21d6bf0..0cd298851ea1 100644 > --- a/net/ethtool/pse-pd.c > +++ b/net/ethtool/pse-pd.c > @@ -227,8 +227,11 @@ ethnl_set_pse_validate(struct ethnl_req_info *req_info, struct genl_info *info) > struct nlattr **tb = info->attrs; > struct phy_device *phydev; > > + rtnl_lock(); > phydev = ethnl_req_get_phydev(req_info, tb[ETHTOOL_A_PSE_HEADER], > info->extack); > + rtnl_unlock(); RTNL lock must be held until the PHY device is no longer being used, as it may disappear at any point [1]. RTNL protects against that. The first iteration of your patch had the right idea, as the lock was released at the end of the function. [1] : https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/net/ethtool/netlink.h#n281 Thanks, Maxime
Hi Maxime Thanks for the clarification, I missed that. Should I resend my first patch or should I release the lock before every return (tbh, I feel like that may lead to a lot of repeated code) and send a new patch? Thanks, Diogo Jahchan Koike
Hi Diogo, Le 26/08/2024 à 19:00, Diogo Jahchan Koike a écrit : > [Vous ne recevez pas souvent de courriers de djahchankoike@gmail.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ] > > Hi Maxime > > Thanks for the clarification, I missed that. Should I resend my first patch > or should I release the lock before every return (tbh, I feel like that may > lead to a lot of repeated code) and send a new patch? > Do not duplicate release lock before every return. See https://docs.kernel.org/process/coding-style.html#centralized-exiting-of-functions Christophe
Hi Cristophe Yes, thanks for reviewing, I will just resend my first patch that used the out label now that I am aware that the lock has to be held during all interactions with the device. Thanks, Diogo Jahchan Koike
diff --git a/net/ethtool/pse-pd.c b/net/ethtool/pse-pd.c index 507cb21d6bf0..0cd298851ea1 100644 --- a/net/ethtool/pse-pd.c +++ b/net/ethtool/pse-pd.c @@ -227,8 +227,11 @@ ethnl_set_pse_validate(struct ethnl_req_info *req_info, struct genl_info *info) struct nlattr **tb = info->attrs; struct phy_device *phydev; + rtnl_lock(); phydev = ethnl_req_get_phydev(req_info, tb[ETHTOOL_A_PSE_HEADER], info->extack); + rtnl_unlock(); + if (IS_ERR_OR_NULL(phydev)) { NL_SET_ERR_MSG(info->extack, "No PHY is attached"); return -EOPNOTSUPP;
ethnl_req_get_phydev should be called with rtnl lock held. Reported-by: syzbot+ec369e6d58e210135f71@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ec369e6d58e210135f71 Fixes: 31748765bed3 ("net: ethtool: pse-pd: Target the command to the requested PHY") Signed-off-by: Diogo Jahchan Koike <djahchankoike@gmail.com> --- net/ethtool/pse-pd.c | 3 +++ 1 file changed, 3 insertions(+)