Messages in this thread Patch in this message | | | From | youngjun <> | Subject | [PATCH] kernfs: fix possibility of NULL pointer dereference. (mount.c) | Date | Mon, 27 Apr 2020 10:32:02 -0700 |
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mount.c also uses "kernfs_dentry_node". When dentry is negative, "kernfs_dentry_node" returns NULL. In this case, "kernfs_root" dereferences NULL pointer.
Signed-off-by: youngjun <her0gyugyu@gmail.com> --- fs/kernfs/mount.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index 9dc7e7a64e10..cd49cb936681 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -23,19 +23,33 @@ struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache; static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry) { - struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry)); - struct kernfs_syscall_ops *scops = root->syscall_ops; + struct kernfs_node *node = kernfs_dentry_node(dentry); + struct kernfs_root *root; + struct kernfs_syscall_ops *scops; + + if (node) { + root = kernfs_root(node); + scops = root->syscall_ops; + } else + return 0; if (scops && scops->show_options) return scops->show_options(sf, root); + return 0; } static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry) { struct kernfs_node *node = kernfs_dentry_node(dentry); - struct kernfs_root *root = kernfs_root(node); - struct kernfs_syscall_ops *scops = root->syscall_ops; + struct kernfs_root *root; + struct kernfs_syscall_ops *scops; + + if (node) { + root = kernfs_root(node); + scops = root->syscall_ops; + } else + return 0; if (scops && scops->show_path) return scops->show_path(sf, node, root); @@ -138,6 +152,9 @@ static struct dentry *kernfs_get_parent_dentry(struct dentry *child) { struct kernfs_node *kn = kernfs_dentry_node(child); + if (!kn) + return NULL; + return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent)); } -- 2.17.1
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