This bug could cause oopses and page state corruption, because ncpfs used the generic page-cache symlink handlign functions. But those functions only work if the page cache is guaranteed to be "stable", ie a page that was installed when the symlink walk was started has to still be installed in the page cache at the end of the walk. We could have fixed ncpfs to not use the generic helper routines, but it is in many ways much cleaner to instead improve on the symlink walking helper routines so that they don't require that absolute stability. We do this by allowing "follow_link()" to return a error-pointer as a cookie, which is fed back to the cleanup "put_link()" routine. This also simplifies NFS symlink handling.
Showing the changes to include/linux (1 of 10 files). Show all
Unified · Split
| @@ -993,8 +993,8 @@ struct inode_operations { · 992 unmodified lines | ||
| 993 | 993 | int (*rename) (struct inode *, struct dentry *, |
| 994 | 994 | struct inode *, struct dentry *); |
| 995 | 995 | int (*readlink) (struct dentry *, char __user *,int); |
| 996 | − int (*follow_link) (struct dentry *, struct nameidata *); | |
| 997 | − void (*put_link) (struct dentry *, struct nameidata *); | |
| 996 | + void * (*follow_link) (struct dentry *, struct nameidata *); | |
| 997 | + void (*put_link) (struct dentry *, struct nameidata *, void *); | |
| 998 | 998 | void (*truncate) (struct inode *); |
| 999 | 999 | int (*permission) (struct inode *, int, struct nameidata *); |
| 1000 | 1000 | int (*setattr) (struct dentry *, struct iattr *); |
| @@ -1602,8 +1602,8 @@ extern struct file_operations generic_ro_fops; · 601 unmodified lines | ||
| 1602 | 1602 | extern int vfs_readlink(struct dentry *, char __user *, int, const char *); |
| 1603 | 1603 | extern int vfs_follow_link(struct nameidata *, const char *); |
| 1604 | 1604 | extern int page_readlink(struct dentry *, char __user *, int); |
| 1605 | −extern int page_follow_link_light(struct dentry *, struct nameidata *); | |
| 1606 | −extern void page_put_link(struct dentry *, struct nameidata *); | |
| 1605 | +extern void *page_follow_link_light(struct dentry *, struct nameidata *); | |
| 1606 | +extern void page_put_link(struct dentry *, struct nameidata *, void *); | |
| 1607 | 1607 | extern int page_symlink(struct inode *inode, const char *symname, int len); |
| 1608 | 1608 | extern struct inode_operations page_symlink_inode_operations; |
| 1609 | 1609 | extern int generic_readlink(struct dentry *, char __user *, int); |