On Wed 16-10-24 14:37:19, Alessandro Zanni wrote: > Fix uninitialized value issue in from_kuid by initializing the newattrs > structure in do_truncate() method. Thanks for the fix. It would be helpful to provide a bit more information in the changelog so that one doesn't have to open the referenced syzbot report to understand the problem. In this case I'd write something like: ocfs2_setattr() uses attr->ia_uid in a trace point even though ATTR_UID isn't set. Initialize all fields of newattrs to avoid uninitialized variable use. But see below as I don't think this is really the right fix. > Fixes: uninit-value in from_kuid reported here > https://syzkaller.appspot.com/bug?extid=6c55f725d1bdc8c52058 Fixes tag should reference some preexisting commit this patch is fixing. As such this tag is not really applicable here. Keeping the syzbot reference in Reported-by and Closes (or possibly change that to References) is good enough. > Reported-by: syzbot+6c55f725d1bdc8c52058@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://syzkaller.appspot.com/bug?extid=6c55f725d1bdc8c52058 > Signed-off-by: Alessandro Zanni <alessandro.zanni87@xxxxxxxxx> > --- > fs/open.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/open.c b/fs/open.c > index acaeb3e25c88..57c298b1db2c 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -40,7 +40,7 @@ int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry, > loff_t length, unsigned int time_attrs, struct file *filp) > { > int ret; > - struct iattr newattrs; > + struct iattr newattrs = {0}; We usually perform such initialization as: struct iattr newattrs = {}; That being said there are many more places calling notify_change() and none of them is doing the initialization so this patch only fixes that one particular syzbot reproducer but doesn't really deal with the problem. Looking at the bigger picture I think the right solution really is to fix ocfs2_setattr() to not touch attr->ia_uid when ATTR_UID isn't set and similarly for attr->ia_gid and ATTR_GID. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
